Noticed that when I set a selection to grow in a random direction, it
instead grew in all directions, which is not what I wanted. Turns out
the -1 random dir ended up being passed straight to the code which
checks bitmasks, without any form of randomizing among directions.
So this adds code to do that, and defines W_RANDOM as -1 rather than
using a magic number. In the process I also noticed that specifying
"random" as the wall for a door in a room made it rerandomize the
direction every iteration of its loop, essentially rolling two rn2(4)s
and only proceeding if they matched. That was pointless so I cleaned it
up a bit.
Also added safety checks in the form of an impossible for des.corridor()
being called with "random" as either walldir, because this is not
implemented currently.
And lastly, I noticed that create_secret_door was entirely unused
(secret door creation is handled in create_door), so I deleted it.
The only behavior change caused by this is that the Valkyrie quest lava
pools will be a little smaller, which is the only place grow is
currently used. If it's desired to keep them the same, that should be
changed to "all".