(INCOMPLETE) Parse rooms from XML

* Create addModifier() to Interactable and InteractableItem classes to
add a value that modifies a member variable. AKA overriding the
observation, inspection, name, badInteraction, or number of uses of
the object.
* Create MapParser super class for parsers to inherit from.
* Create RoomParser class to parse Interactable and InteractableItems
into a specific room.
    * TODO: Parse the connecting rooms into the room.
* Create Room class to store all Interactables.
    * TODO: Store connecting rooms.
* Create RoomParserTest to do a preliminary test of RoomParser.
* TODO: Create RoomTest.
Merge branch 'squashed_feature'