add copy-constuctor to WeightedMap
reformat CalcStaircases a little bit more for it be usable elsewhere
generalize dig cell methods to be usable with any WeightedMap
generalize dig room method to be usable with any WeightedMap
add Direction constructor with initial direction
remove const from Room's fields for default assignment operator
fix copy constructor for WeightedMap
implement WeightedMap::operator=
add mostly working solution for up staircases positioning near rooms