Most of the functionality of gfx_render_texture (draw method, blend
rate) is moved into sprite_render, since this was the only place using
it.
The draw method and blend rate are now stored in sact_sprite objects
instead of textures.
sact_sprite now has two renderers: the old SACT2 renderer (with blend
rate as the only shader parameter) and the new ChipmunkSpriteEngine
renderer, which supports multiply/add colors and the "surface area"
feature from PartsEngine.
Rance Quest now runs up to the first Flash-related function call
(Flash?!?!).
