[OPEN] Can't place stairs after bulldozing penthouses/multi-story

@SivILCC I was able to duplicate this issue in my game.  This problem applies not only to penthouse apartments but to any multi-story apartment.  If you bulldoze the apartment, you will be unable to place stairs unless you first redraw room(s) in which to place them or place them against the edge of the apartment.  The error message that appears is "Bottom of stairs are off lot" and the visual shows a red triangle far overhead.  Will add to our list.