Renamed TaigaActor::container to TaigaActor::state for consistency.
Don't tell users that there is no good reason to
access TaigaActor::state. There is.
Made x and y coordinates be part of the TaigaDrawer class.

This is a necessary step toward adding layer cameras.
Moved TaigaDrawer member functions to TaigaRender.cpp
Added comments to TaigaRender.h