private ExpandRoomComplete calculate_doors(ExpandRoom p_room){
  SortedRoomsTop calculator=new SortedRoomsTop(this);
  return calculator.calculate(p_room);
}

private ExpandRoomComplete calculate_doors ( ExpandRoom p_room ) { SortedRoomsTop calculator = new SortedRoomsTop ( this ) ; return calculator . calculate ( p_room ) ; }
calculates the neighbours of p_room and inserts doors to the new created neighbour rooms . the shape of the result room may be different to the shape of p_room
