Updates to the Modify Existing capabilities

1. Fixed some bugs related to modifying walls, floors, and roofs by
closed profile.
2. Floors and Roofs can now be modified without replacing the sketch if
the number of sketch lines that define it equals the quantity of
incoming curve segments.  This modified elements can retain their hosted
objects, but you still run the risk of losing dimensions if it changes
too much.
3.  Wall's cannot seem to be modified in the same way as roofs and
floors so they will still have to be recreated and therefore lose hosted
elements every time you update a closed profile based (as opposed to
wall centerline based) wall.