Completed room loader. Major fixes to room. Added test adventure for rooms.

* pyoo/interpret.py: Interpreter: Added a place cache for looking up places by name.
                             remove try around handle_enter and handle_move.

* pyoo/placeloader.py: New class. Loads a simple textual fomat for a set of potentially connetcted places.

* pyoo/things.py: Added go <direction> verb to Place.
             Separated go mechanic to do_go.

* roomtest.txt: A small set of connected places to test PlaceLoader.
* testrooms.py: A small adventure that loads roomtest.txt, demonstrating
                PlaceLoader and subclassing Place.