ChessMod

I was fiddling to get in some of the design work and lay the groundwork for 0.70 release and got sidetracked by meetings and life... but also fiddled the knight so that the way it looks no longer bugs me so much. The code for drawing the knight is also less gross and we're a tiny bit closer to being able to have the board oriented as placed (the TileEntityRender, what you see when walking around the world).

For anyone who's curious, but doesn't want to look at code, there's now starting to be more documentation around the mod side, gradually making it follow the suggested approaches for Forge 1.16.5. The other change that's made it into this release is some field name changes so everything is uniform in following that convention for ids, e.g. gold_chessboard instead of GOLD_CHESSBOARD.