Blender Git Loki

NLA SoC: Code for basic evaluation of NLA strips done

In theory, actions can now be evaluated in NLA, though in practice, we don't have an NLA Editor to create data to use this yet! Next up, transitions...

Some notes:
* Recoded the way the 'accumulation' methods work (i.e. blend, add, etc.), adding a few new ones. It should now be more obvious how these work.
* Some assorted code cleanups done too (removing unneeded vars/args)