don't store bevel weights or edge crease customdata layers in editmode unless they are needed.

configurable in 'Geometry Data' panel, will be added when running crease edges transform for example.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53690 954f8c5b-7b00-dc11-b283-0030488c597c