the match freeze code doesn't need DONT_SNAP
fixed bug in layer top flagger

by checking every vertex with
the LAYER flag, the top flagger
was failing to find a number on
the apex vertex of pyramids in
meshes with height differences.
those will never be considered
top vertices, so restrict the search
to numbered vertices.
remove unneeded variable
fix bug in growth curve top finder

the previous algorithm would fail
to find some tops around layer
height changes
prevent snapping from affecting matched entities
allow snapping in chef UR