Added Inventory, items can now be picked up(but not yet dropped)

-Player avatars now have an inventory
-'inventory' command and 'i' alias added
-ability to use 'look' and 'examine' on items in inventory now available
-'get' command added
-Items all correctly move between inventories, and only exist in one
place at a time as expected
-Added various messages for poorly formed 'look' and 'examine' commands