Started working on text adventure demo

    Created a series of projects:
    - TextAdventure.Core will contain the engine of the text adventures
    - TextAdventure.Core.UnitTests will contain unit tests for the project above
    - CaveAdventure will contain the Colossal Cave Adventure

    I have started working on basic skeleton/infrastructure in the text adventure
    engine to display the description of the first room of a given text adventure.
Updated the domain model to avoid cycles

    I updated the domain model to avoid cycles when navigating
    between Rooms. To avoid cases such as Room 1 is connected to
    Room 2, and Room 2 is connected to Room 1 that is connected to
    Room 2, ad infinitum xD.

    In this new version we store room document references instead of
    the actual rooms.
Added the game loop, support for moving between rooms and performing arbitrary actions