Returns a room pointer for the given entity parameter or null on failure.      If @entity is set to a room pointer then it is checked for validity and     returned if valid. Alternatively if @entity is set to an integer value     then a pointer to the room (if any) with that vnum is returned.  Finally     if @entity is a pointer to a mobile or object then a pointer to the room     in which the mobile or object resides is returned.
      Examples:              @room = %getRoomPointer( @n )
          @room = %getRoomPointer( 115611 )  |