Updated GlobalContext, HistoricRecord, Game, Dungeon, Floor, Square and Character

- Added GlobalContext's methods to add Characters and Dungeons
- Added GlobalContext's methods to start and to end a game
- Added Game constructor (used un GlobalContext start Game method) that initialize an HistoricRecord
- Added HistoricRecord's constructor(used in Game's constructor) that initialize the record with current date and properties that sets the end's Game date (used in GlobalContext end methods)
- Dungeon updated to support entrance and exit Square
- Dungeon no longer retain the level of the Floor
- Dungeon's tests updated to support GlobalContext's container
- Floor updated to support his level
- Floor's tests updated to support GlobalContext's container
- Square updated to support TeleportTo attribute
- Square's tests updated to support GlobalContext's container
- Character updated to support GlobalContext's container and "not in Dungeon at creation" paradigm