This allows Godot to automatically compress meshes to save a lot of bandwidth.
In general, this requires no interaction from the user and should result in
no noticable quality loss.
This scheme is not backwards compatible, so we have provided an upgrade
mechanism, and a mesh versioning mechanism.
Existing meshes can still be used as a result, but users can get a
performance boost by reimporting assets.
-Mesh2D now works
-MultiMesh2D now works
-Polygon2D now works
-Added hooks for processing 2D particles
-Skeleton2D now works
2D particles still not working, but stuff needed for it is now implemented.
-Used a more consistent set of keywords for the shader
-Remove all harcoded entry points
-Re-wrote the GLSL shader parser, new system is more flexible. Allows any entry point organization.
-Entry point for sky shaders is now sky().
-Entry point for particle shaders is now process().
