navigation and the n/e/w/s commands

support for travelling. rooms have descriptions which are printed in
full the first time you visit them. All navigation makes a room.enter()
call now, so we can include functionality there if need be - doors that
shut behind you, long-drops, alarms going off, whatever
single word commands in Understand - news, i, look

NEWS: Travels.
i: Prints inventory. Probably we also accept "inventory", eventually.
look: Without a noun, looks at the current room.