<Languages>
    <Language>
        <Name>D</Name>
        <Extensions>
            <Extension>d</Extension>
            <Extension>di</Extension>
        </Extensions>
        <Compilers>
            <Compiler>
                <Application>dmd</Application>
                <CompileCommand>{cmd} -c {source} -of{ObjectDir}/{source}.obj {includesArgument}</CompileCommand>
                <LinkCommand>{cmd} {objects} {libraries} -of{OuputDir}/{name}{extension} {includes}</LinkCommand>
                <IncludesArgument> -I{include}</IncludesArgument>
                <StaticLibraryArgument> -lib</StaticLibraryArgument>
                <DynamicLibraryArgument> -lib</DynamicLibraryArgument>
                <Platforms>
                    <Platform>
                        <Type>windows</Type>
                        <Targets>
                            <Target>win32</Target>
                            <Target>win64</Target>
                        </Targets>
                        <CompilerLocation>C:/D/dmd2/windows/bin/</CompilerLocation>
                        <StandardLibrary include="false">C:/D/dmd2/windows/lib/phobos.lib</StandardLibrary>
                        <BinaryExtension>.exe</BinaryExtension>
                        <DynamicLibraryExtension>.dll</DynamicLibraryExtension>
                        <StaticLibraryExtension>.lib</StaticLibraryExtension>
                        <Compatibility>
                        </Compatibility>
                    </Platform>
                    <Platform>
                        <Type>linux</Type>
                        <BinaryExtension></BinaryExtension>
                        <DynamicLibraryExtension>.so</DynamicLibraryExtension>
                        <StaticLibraryExtension>.a</StaticLibraryExtension>
                        <Compatibility>
                            <Language objectsOnly="true">c</Language>
                        </Compatibility>
                    </Platform>
                </Platforms>
                <Profiles>
                    <Profile default="true">
                        <Name>Release</Name>
                        <LinkCommand> -release</LinkCommand>
                    </Profile>
                    <Profile>
                        <Name>Debug</Name>
                        <CompileCommand> -debug -gc</CompileCommand>
                        <LinkCommand> -debug -gc</LinkCommand>
                    </Profile>
                    <Profile>
                        <Name>Unittest</Name>
                        <CompileCommand> -unittest -gc</CompileCommand>
                        <LinkCommand> -unittest -gc</LinkCommand>
                    </Profile>
                </Profiles>
                <Project>
                    <SourceDir>{project_dir}/src</SourceDir>
                    <OutputDir clean="true">{project_dir}/bin/{target}</OutputDir>
                    <ObjectDir clean="true">{project_dir}/obj/{target}</ObjectDir>
                    <ResourceDir>{project_dir}/resources</ResourceDir>
                    <Includes>
                    </Includes>
                    <ProvidesModules>
                    </ProvidesModules>
                    <target>{hostPlatform}</target>
                </Project>
            </Compiler>
        </Compilers>
    </Language>
    <Language>
        <Name>C</Name>
        <Extensions>
            <Extension>c</Extension>
        </Extensions>
        <Compilers>
            <Compiler>
                <Application>gcc</Application>
                <CompileCommand>{cmd} -c {source} -o{ObjectDir}/{source}.obj {includesArgument}</CompileCommand>
                <LinkCommand>{cmd} {objects} {libraries} -o{OuputDir}/{name}{extension} {includes}</LinkCommand>
                <IncludesArgument> -I{include}</IncludesArgument>
                <StaticLibraryArgument> -lib</StaticLibraryArgument>
                <DynamicLibraryArgument> -lib</DynamicLibraryArgument>
                <Platforms>
                    <Platform>
                        <Type>windows</Type>
                        <Targets>
                            <Target>win32</Target>
                            <Target>win64</Target>
                        </Targets>
                        <CompilerLocation>C:/MinGW/bin/</CompilerLocation>
                        <BinaryExtension>.exe</BinaryExtension>
                        <DynamicLibraryExtension>.dll</DynamicLibraryExtension>
                        <StaticLibraryExtension>.lib</StaticLibraryExtension>
                        <Compatibility>
                            <Language objectsOnly="true">C++</Language>
                        </Compatibility>
                    </Platform>
                    <Platform>
                        <Type>linux</Type>
                        <BinaryExtension></BinaryExtension>
                        <DynamicLibraryExtension>.so</DynamicLibraryExtension>
                        <StaticLibraryExtension>.a</StaticLibraryExtension>
                        <Compatibility>
                            <Language objectsOnly="true">C++</Language>
                            <Language objectsOnly="true" requireStandardLibrary="true">D</Language>
                        </Compatibility>
                    </Platform>
                </Platforms>
                <Profiles>
                    <Profile default="true">
                        <Name>Release</Name>
                    </Profile>
                    <Profile>
                        <Name>Debug</Name>
                        <CompileCommand> -ggdb</CompileCommand>
                        <LinkCommand> -ggdb</LinkCommand>
                    </Profile>
                </Profiles>
                <Project>
                    <SourceDir>{project_dir}/src</SourceDir>
                    <OutputDir clean="true">{project_dir}/bin/{target}</OutputDir>
                    <ObjectDir clean="true">{project_dir}/obj/{target}</ObjectDir>
                    <ResourceDir>{project_dir}/resources</ResourceDir>
                    <Includes>
                        <Include>{project_dir}/headers</Include>
                    </Includes>
                    <ProvidesModules>
                    </ProvidesModules>
                    <target>{hostPlatform}</target>
                </Project>
            </Compiler>
        </Compilers>
    </Language>
    <Language>
        <Name>C++</Name>
        <Extensions>
            <Extension>cpp</Extension>
        </Extensions>
        <Compilers>
            <Compiler>
                <Application>g++</Application>
                <CompileCommand>{cmd} -c {source} -o{ObjectDir}/{source}.obj {includesArgument}</CompileCommand>
                <LinkCommand>{cmd} {objects} {libraries} -o{OuputDir}/{name}{extension} {includes}</LinkCommand>
                <IncludesArgument> -I{include}</IncludesArgument>
                <StaticLibraryArgument> -lib</StaticLibraryArgument>
                <DynamicLibraryArgument> -lib</DynamicLibraryArgument>
                <Platforms>
                    <Platform>
                        <Type>windows</Type>
                        <Targets>
                            <Target>win32</Target>
                            <Target>win64</Target>
                        </Targets>
                        <CompilerLocation>C:/MinGW/bin/</CompilerLocation>
                        <BinaryExtension>.exe</BinaryExtension>
                        <DynamicLibraryExtension>.dll</DynamicLibraryExtension>
                        <StaticLibraryExtension>.lib</StaticLibraryExtension>
                        <Compatibility>
                            <Language>C</Language>
                        </Compatibility>
                    </Platform>
                    <Platform>
                        <Type>linux</Type>
                        <BinaryExtension></BinaryExtension>
                        <DynamicLibraryExtension>.so</DynamicLibraryExtension>
                        <StaticLibraryExtension>.a</StaticLibraryExtension>
                        <Compatibility>
                            <CompatibilityLanguage>C</CompatibilityLanguage>
                            <CompatibilityLanguage objectsOnly="true" requireStandardLibrary="true">D</CompatibilityLanguage>
                        </Compatibility>
                    </Platform>
                </Platforms>
                <Profiles>
                    <Profile default="true">
                        <Name>Release</Name>
                    </Profile>
                    <Profile>
                        <Name>Debug</Name>
                        <CompileCommand> -ggdb</CompileCommand>
                        <LinkCommand> -ggdb</LinkCommand>
                    </Profile>
                </Profiles>
                <Project>
                    <SourceDir>{project_dir}/src</SourceDir>
                    <OutputDir clean="true">{project_dir}/bin/{target}</OutputDir>
                    <ObjectDir clean="true">{project_dir}/obj/{target}</ObjectDir>
                    <ResourceDir>{project_dir}/resources</ResourceDir>
                    <Includes>
                        <Include>{project_dir}/headers</Include>
                    </Includes>
                    <ProvidesModules>
                    </ProvidesModules>
                    <Target>{hostPlatform}</Target>
                    <Repositories>
                        <Repository>
                            <Name>Main Repository</Name>
                            <BaseURL>http://example.com/repo</BaseURL>
                        </Repository>
                        <Repository>
                            <Name>Local repository</Name>
                            <Directory>{bspDataDir}/repo</Directory>
                        </Repository>
                    </Repositories>
                </Project>
            </Compiler>
        </Compilers>
    </Language>
</Languages>

If targets is not specified for a platform of a compiler then check
against it's type.
The type insignifies the binary of the compiler is in. Not the output it produces.
The output of a compiler is the type.
The type should match one of these:
    windows
    linux
    osx
    freeBSD
    solaris
    posix
Targets are made up of the platform and a more specific information.
    win32
    win64

<Project>
    <Name>ABC project</Name>
    <Version>x.y.z</Version>
    <Description>An amazing project!</Description>
    <Profile>Release</Profile>
    <ProvidesModules>
        <Module>project.abc.test</Module>
    </ProvidesModules>
    <Developers>
        <Developer>Person here [email protected]</Developer>
    </Developers>
    <VCS>https://example.com/repo/abc.git</VCS>
    <URL>http://example.com/project/abc</URL>

    <Dependencies>
        <Dependency>
            <Name>DEF project</Name>
            <Version>i.j.k</Version>
            <Module>project.def.test</Module>
            <Directory>{ProjectDir}/../DEF</Directory>
        </Dependency>
    </Dependencies>
</Project>

Configuration 'flattening' occurs in these steps
1. Load all files and keep output seperate
2. Create list of all languages which have unique names
3. Add to list of languages a new version of each language that has conflicts
    If append is available append to previous value for property otherwise overide.
    Prefer the later files not the first ones.
4. For each project in languages create a new one and use it as the base then overlay the projects configuration.
5. For each project created in last step gather the application, compile command, link command, includes, dynamic library and static library arguments.
6. Create base command to be executed for each project for storage.

Make sure 1-4 can be made into a cached file. (Preferably a mmfile).

Folder structure
~/.bsp/languages.xml
e.g. ~/.bsp/repo/m.o.d.u.l.e/v.e.r.s.i.o.n/project.xml
e.g. ~/.bsp/repo/m.o.d.u.l.e/v.e.r.s.i.o.n/languages.xml
e.g. ~/.bsp/repo/m.o.d.u.l.e/v.e.r.s.i.o.n/src
e.g. ~/.bsp/repo/m.o.d.u.l.e/v.e.r.s.i.o.n/bin/win32/bin.dll
e.g. ~/.bsp/repo/m.o.d.u.l.e/v.e.r.s.i.o.n/bin/win32/bin.lib
project_dir/project.xml
project_dir/languages.xml
project_dir/project_cached.xml
e.g. project_dir/bin/win32/bin.dll
e.g. project_dir/src
e.g. project_dir/obj/win32/bin.obj
e.g. project_dir/obj/win32/dependencies/m.o.d.u.l.e/bin.lib
e.g. project_dir/resources