Refine.lsp
This routine will add vertices to the midpoints of lwpolyline segments.
There is very little error checking;
it will currently choke on 3d (open space) polylines, though this capability could be added fairly easily.
It might also have problems on sets of lwpolylines created in different User Coordinate systems. I'll address
these contingencies as they are needed.
When the process is complete, the user can choose to erase the originals (the default is to keep them,
in which case, they become the user's "previous" selection set - making it easy to retire them to another
layer, etc.)
