Blender Git Loki

remove short int -> float conversion for vertex normals

Performance experiment �?? thought this might be slowing down large
shaded meshes on Mac + nVidia but it was not. Index buffers in VRAM
fixed the perf issue :)

Keeping normals as GL_SHORT uses less memory. Would be 1/2 but
padding/alignment makes it 2/3. These stay GL_SHORT in VRAM also, and
are converted to floats when loaded by the vertex shader.