Adds getSquare()
Fixes addSquare
Removes a (now deprecated) method.
Minor advances on optimization
Merges addRoom and createRoom
Adds hashCode()
Now uses HashSet where it should.
Adds isPositionUsed
Changes on CreateRoom and aux methods
Adds a few functionalities and solves a few bugs.

- 'n' creates a new Dungeon
- RightArroow creates 10 rooms
- Solves a bug with doors
- Other minor stuff
Cleans a bit and adds comments for future work.