Was already done for immediate mode, but rearranged code to make a clean separation. Cleaned up #includes for code that uses this feature.
Added same for batched rendering.
Vertex Buffer to store vertex attribute data.
Element List (AKA Index Buffer) to select which vertices to use.
Batch combines these into an object that can be built once then drawn
many times.
Porting over from the C++ version… Most of this C code is compiled but
unused. Some of it is not even compiled. Committing now in case I’m
lost at sea.
