fix [#35311] Planar Decimate / Limited Dissolve fails to merge some adjacent faces
optionally limit by face flipping, also added support to delimit by material and edge crease.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57216 954f8c5b-7b00-dc11-b283-0030488c597c