Implementation of the room hierarchy

[Koldar]

AS a developer
I WANT to have some hierarchy managing a room in the maze
BECAUSE in this way we can have a model of the room that can be used throughout the whole project

The maze is a graph of rooms. The rooms is an incredible important concept inside the game, hence we need to properly design it. Thanks to @micheledusi and @majik00027 we already have a UML diagram of the room. We just need someone to implement in Unity such model.

The model should include a generic interface of the room (eg. IRoom) because in this way the project will just use IRoom everywhere and not the actual concrete class: this should enhance modularity.

No rendering in unity of the room is needed to complete this task.