Blender Git Loki

Fix for 2042

With the new rule that allows correct calculation of vertex normals on a
mixed solid/smooth mesh, it is essential that vertex normals get
recalculated when changing smooth settings. Such a facility doesnt exist
in Blender yet, only after leaving editmode.
Hacking in a "enter editmode, leave editmode" event on the "Set Smooth"
button isn't nice... instead I've tweaked the calculus of vertexnormals
that it always sets them OK, apart from where they get mixed with solid
faces. Only in rare occasions this can still go "wrong" and needs a
TAB-TAB to fix. Will add that comment in release notes. For next release
we should definitely solve this smoothing bizz!