new bevel: fix for crash in merge, could result in collapsing faces being invalid. rather then splice each edge, use weld_verts operator which handles removing degenerate geometry.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56768 954f8c5b-7b00-dc11-b283-0030488c597c