fix for glitch with vertex bake:
- the mesh would be tagged to update, then updated before bake finished.
- also increase self-shadow offset, in some cases the offset wasn't enough.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54015 954f8c5b-7b00-dc11-b283-0030488c597c