adventure.game now handles execution of game events.  No support for adding external event listeners yet.

Finally the starting room name and description are printed to the screen when the game begins..

Cleans up some documentation ambiguity between actions and commands.  Still some cleanup left to be done.  For future reference, actions are things the player can do, while commands wrap an action together with the objects to be acted upon, the player input that produced the command, and the results of the command.