Merge branch 'master' of
https://github.com/GrueAdventures/AdventureMaker.git
I worked on making Player more consistent.  Instead of manipulating
Player with ID strings, I changed it to objects.  Classes that use
player will be responsible for finding the object to add/remove and all
of that fun stuff.  I think this simplifies the job of the Player, a
tricky class, significantly.
ItemBag is for keeping track of instantiated items.  This is useful for
dealing with player.