Update renderer design to be more flexible and data-driven based on material and shader definitions.
Support conditional expressions in shader effect XML files.
Consolidate fixed-function model rendering into the shader system.
Remove lots of now-obsolete renderer code.
Move shader defines from std::map to new class with interned data, for performance.
Move texture from model into material.
Alleviate singletonitis.
Remove obsolete lodbias setting.
Remove unused terrain shadow transparency.