Don't prompt about irrelevant transformations while in stat death.

Not sure if a transform that worsens your state should prompt, but since
for purposes other than recovery stats are floored at 0, it's probably
ok without a prompt -- and this doesn't require handling extra wording.
Simplify and constify.
Sort artefact brands by their chance rather than enum.
Drop some randart power_level oddities.
Djinn: no contact with the ground means less Shatter damage.

Same as Airstrike.
Let the rN mutation work when transformed.

It's not a physical attack, so I'd expect it to work the same on all
forms that don't get rN by themselves.  Also, torment resistance works
when transformed already.
Djinn: convert innate rN+++ to a mutation.

The mutation disabling itself when transformed was not an issue for
mummies and ghouls as they can't transform at all.  With it working
all the time, we don't need to handle demonic/angelic spiders/etc
losing their rN+++.
Djinn: duplicate innate resistances on '%'.

I fail to see the point, though.
Adjust some wall tile weights
Beogh altar

With thanks to Bloax.