Litematica quick howto for the development version

Generic tips:
- Main menu by default is M (when released)
- The in-game configs menu is M + C
- The Area Selections menu is M + S
- The Schematic Placements menu is M + P
- Configuration GUI is numpad subtract, when having "a thing" selected (area selection, or schematic placement)
- When using the tool to place corners, you can sneak to inset the position inside the targeted block, instead of adjacent to it
- When having something (a box, corner, or placement) selected, you can hold the "Nudge modifier" (left Alt by default) and scroll while holding the tool (in the appropriate mode)
  to nudge around the selected element in the player's looking direction
- There is another modifier, the "Grab modifier" which moves the entire area selection when having the origin selected

Quick tutorial for creating a schematic:
- Get a "tool item", by default that's a stick, you can change it in the Generic configs to whatever item
- Ctrl + scroll while holding that item to change to the Area Selection mode [1/7]
- M + S (or via the main menu) to open the Area Selection GUI
- Select an existing one, or create a new selection - that name will also be used for the saved schematic by default
- Now that you have a selection, M + A adds the first box
- With the first box, you also get the origin point moved to your position, and the origin is selected by default (the origin is the orange box when unselected
- Any selected element/corner is cyan/light blue/whatever
- First move that origin point to a suitable place (left click), then middle click the red box to select it
- Left/right click and/or left Alt + scroll to place/move the selections around, middle click with the tool to select elements or corners
- Left click moves the "first/primary" red corner, right click the second corner (blue) when you have a sub-region box or corner selected
- M + A to add more "sub-region boxes" if needed, again middle/left/right click to select and move stuff
- Hit numpad subtract to rename the selected sub-region box, if needed
- These sub-region names can NOT be renamed later, and they will be used for the schematic sub-regions, so descriptive names are nice at least for technical contraptions
- Hit Ctrl + S to save it as a schematic to file
- Or Ctrl + Alt + S to only save it as a temporary in-memory-only schematic

About creating or importing schematics:
- One option is to convert an existing Schematica schematic using the Schematic Manager menu to "Import" it - this will save it in the Litematica format
  > The imported schematics have the downside that they, as the original schematic as well, only have one huge sub-region box around the entire thing
  > These also won't have any inventory contents saved, at least if the original schematic was made with Schematica
  > MCEdit does save the inventories, I'm pretty sure
- The best way to get a Litematica schematic (unless one is available for download already obviously...)
  is to create one from a world download, or use MCEdit to place the original non-Litematica schematic to a temporary world
- Making a proper Litematica schematic from a world download (or pasting the original with MCEdit to a temp world) allows you to use sub-regions
  to capture "tightly grouped"/individual parts of the contraption, and to name those sub-regions appropriately
  > May be useful if you want to disable some sub-regions while building stuff
- Making a Litematica schematic (in single player!) also allows properly storing all inventory contents, which will be visible in the info overlay
  ... assuming of course that the inventory contents are in-tact in the first place.
  > So the best way is to make the schematic from a world download
  > Or equally viable is placing a schematic that was originally made with MCEdit into a temporary world using MCEdit - it should also have the inventory contents
  > If you only have a schematic, and the original schematic was made with Schematica, then the inventory contents are not available

Schematic Placements:
- Load a schematic to memory via the Load Schematics menu
- It's highly recommended to load Litematica schematics instead of directly Schematica schematics
  > ... at least if you want the Placement to be persistent between logins or changing the dimension (using portals)
  > Schematica schematics will get converted into in-memory Litematica shematics when loaded directly
  > But them being in-memory-only, they are not persistent, as isn't the Placement if you log out or use a portal
  > This on-the-fly conversion is also orders of magnitude slower than just loading a Litematica schematic
- Tick the Create Placement checkbox to also automatically immediately create a placement of that schematic
- Otherwise, after loading it, go to the Loaded Schematics menu and hit Create Placement for the schematic you want to create a placement for on the list
  > Loaded schematics are a different concept from the "placements" that you create from them
  > You can create an arbitrary number of placements from a single loaded schematic
  > A placement has the position and rotation information etc. and refers to a specific schematic as teh source
- You can change the selected placement and get to the configuration GUI of the placement via the Schematic Placements menu
- Alternatively in the Schematic Placement tool mode [2/7] you can middle click while pointing at the origin box to select the entire placement, or select an individual sub-region by pointing at the sub-region box and middle click with the tool
- (By default) numpad subtract opens the Placement Configuration GUI
  > Note that this exists and is separate both for the entire Placement, and the individual sub-regions of that schematic/placement
  > Which GUI opens depends on what you have selected, but you can also navigate between them in the GUI
- It's possible to move or rotate or disable individual sub-regions
  > The config GUI for the entire placement has an indication for when some of the sub-regions have been "modified" (= moved, rotated, disabled)
  > That indication is the "Reset sub-regions" button being enabled and in orange text