fixed function warnings

Index: binaries/data/mods/public/gui/pregame/mainmenu.js
===================================================================
--- binaries/data/mods/public/gui/pregame/mainmenu.js   (revision 13155)
+++ binaries/data/mods/public/gui/pregame/mainmenu.js   (working copy)
@@ -17,9 +17,24 @@

    EnableUserReport(Engine.IsUserReportEnabled());

-   // Only show splash screen once
-   if (initData && initData.isStartup && Engine.IsSplashScreenEnabled())
-       Engine.PushGuiPage("page_splashscreen.xml", { "page": "splashscreen" } );
+   // Only show splash screen(s) once
+   if (initData && initData.isStartup)
+   {
+       if (Engine.IsSplashScreenEnabled())
+           Engine.PushGuiPage("page_splashscreen.xml", { "page": "splashscreen" } );
+
+       // Warn about deprecated fixed render path
+       if (renderer.renderpath == "fixed")
+           messageBox(
+               600,
+               300,
+               "[font=\"serif-bold-16\"][color=\"200 20 20\"]Warning:[/color] You appear to be using non-shader (fixed function) graphics. This option will be removed in a future 0 A.D. release, to allow for more advanced graphics features. We advise upgrading your graphics card to a more recent, shader-compatible model.\n\nPlease press \"Read More\" for more information or \"Ok\" to continue.",
+               "WARNING!",
+               0,
+               ["Ok", "Read More"],
+               [null, function() { Engine.OpenURL("http://www.wildfiregames.com/forum/index.php?showtopic=16734"); }]
+           );
+   }
 }

 var t0 = new Date;
Index: source/ps/GameSetup/GameSetup.cpp
===================================================================
--- source/ps/GameSetup/GameSetup.cpp   (revision 13155)
+++ source/ps/GameSetup/GameSetup.cpp   (working copy)
@@ -958,6 +958,18 @@
    g_GUI = new CGUIManager(g_ScriptingHost.GetScriptInterface());

    // (must come after SetVideoMode, since it calls ogl_Init)
+   if (ogl_HaveExtensions(0, "GL_ARB_vertex_program", "GL_ARB_fragment_program", NULL)
+       && ogl_HaveExtensions(0, "GL_ARB_vertex_shader", "GL_ARB_fragment_shader", NULL))
+   {
+       DEBUG_DISPLAY_ERROR(
+           L"Your graphics card doesn't appear to be fully compatible with OpenGL shaders."
+           L" In the future, the game will not support pre-shader graphics cards."
+           L" You are advised to try installing newer drivers and/or upgrade your graphics card."
+           L" For more information, please see http://www.wildfiregames.com/forum/index.php?showtopic=16734"
+       );
+       // TODO: actually quit once fixed function support is dropped
+   }
+
    const char* missing = ogl_HaveExtensions(0,
        "GL_ARB_multitexture",
        "GL_EXT_draw_range_elements",