Blender Git Loki

Adding back more functionalities for transform orientations.

Create new orientation is now Ctrl-Alt-Space (Alt-Space is select orientation and the old ctrl-shift-c is taken by add constraints).

New orientation panel in 3d view sidebar (nkey) has operator buttons for select, create and delete. Eventually, this should become a list.

Note that orientation operators are missing notifiers to properly redraw the 3d view and its header properly.