Refactored Forward Rasterizer

LOD and instancing can be used simultaneously
Rasterizer handles multiple databases
Rasterizer sorts drawing by Scene-Program-Textures-Mesh-Object
Rasterizer obeys Scene render flag
Modified Program rasterize method
Renamed Program program attribute to ptr
Removed textures attribute from Program
Added programs attribute to Scene
Added rasterize method to Scene
Added end method to Scene
Mesh stores Program object instead of program name
Mesh properly removes ends itself
Renamed Shader shader attribute to ptr
Cleaned up ID

ID properly handles name changes
Database ends properly by calling down the hierarchy
Cleaned up comments in Scene