Software skinning

Enabling this can greatly reduce drawcalls, and thus improve speed, in games that use the advanced skinning technique used by Tekken, FF:CC and more: To draw a few triangles, upload a few bones, draw few more triangles, etc. Replicating that as-is on current mobile GPUs is very expensive, it's cheaper to just do the transforms in software allowing us to merge the whole skinned mesh into a single drawcall.

Not yet optimized for NEON and can be optimized more, but does reasonable code generation on both x86 and ARM.