Switch all the constant strings in graphics code to use the new
variables.
This avoids the cost of instantiating CStrInterns at runtime every
frame.
This was SVN commit r13906.
Let materials specify shader uniform values.
Use interned strings for shader uniform/attribute names.
Remove confusing float* cast operator on CVector4D.
Simplify and clean up CVector4D.
Remove non-supported 'old' lighting model.
This was SVN commit r11453.
