Dungeon Features:
#  	wall
>  	stairs down (may be omitted)
< 	stairs up   (may be omitted)
C  	map center  (may be omitted)
D  	door        (may be omitted)
'\0'	nothing	    (should occupy every space not defined above)


Layout ideas:
snake layouts (done)
square spirals (like Mwizard maps)  (done)
nethack (actually called "rogue" implemented Jan 16, 2001)
progressive rooms
room and corridor
temple maps
monster placement
decor placement

Other ideas:
riddle-maps with artifact rewards as specials, with reward keyed to difficulty
special-maps with word-activated teleporters and magic mouths as the only
   hint of presense
