Blender Git Loki

[#7289] Orbit around selected in edit mode goes crazy with no verts selected
[#8784] orbiting around selection bug + a few kind of a must features (partial fix)

As suggested by Ton, keep last center and use that when nothing selected.

I don't really like it though as it wouldn't work ok when changing scene or when using a different 3D view and is somewhat non trivial to explain (it's not the last selection, it's the last used orbiting center).