Changing states didn't properly reset between shading groups
causing the GL state to be wrong based on draw order.
States are now only set when changed.
This removes MAX_STORAGE, MAX_BUFFERS, MAX_TEXTURES, MAX_PASSES limits.
Actual memory saving isn't so important, it just means we don't need to
manually bump these based on changes to engines.
All engines are now called by the draw manager. Engines are separate entities that cannot interfer with each others.
Also separated draw_mode_pass.c into the mode engines.
This should give the overall direction to whom wants to finish it.
- Renamed EDIT mode engine to EDIT_MESH mode engine
- Introduce EDIT_ARMATURE mode engine
- Started to port legacy drawarmature.c to draw_armature.c
