Internally UV selection considered close UV's to be connected.
While this could be convenient in some cases,
it complicates logic for more advanced selection operations that
need to check when UV's should be considered part of the same vertex
since simple threshold checks would give different results depending
on the order of UV's tested.
Users must now run "Merge by Distance" instead of relying
on this selection threshold.
and fix Rip Region double proportional checkbox
This fixes the double prop edit checkbox in the redo menu.
This also makes it so that proportional edit in connected mode now
matches how it behaves in mesh edit mode.
Without this change, ripping in UV edit mode with proportional edit on
would be useless as the UV verts you ripped will still be stuck together
even if they were not connected anymore.
Reviewed By: Campbell
Differential Revision: http://developer.blender.org/D8289
