Blender Git Loki

Cleanup: bone cursor picking API

There was one function to access both pose/edit bones,
which returned a void pointer type.

Split these into 3 functions which return EditBone, bPoseChannel or Bone
types.

Internally the logic is still shared, this just makes it clearer to
callers which type is expected.

Also use more conventional prefix for picking API:

- ED_armature_pick_(ebone/pchan/bone)
- ED_armature_pick_(ebone/pchan/bone)_from_selectbuffer