GL3 fixes

-Directional lights now work a lot more correctly (fixes issues
FroggestSpirit was having). Didn't know directional lights needed
normalMatrix instead of modelView matrix.
-Fixes triangleStrip batching in GL3ModelStruct when using indexes. They
were not winding the triangles correctly, so culling failed.
-glsl_program_link() now correctly gets all attributes and uniforms. So
shaders made at runtime work again.