NOPAIN pruning

OK, this knocks back a few NOPAIN calls.  Since most of 'em change
messages, though, not as thorough as I'd like but it's something.

(Includes some work on the sleep-state traits too.  Forgot to commit
earlier.)
Less sleep

Gives a chance every half-hour not to take fatigue.  You can start with
one_in 6, Alpha can get 1/4 post-Threshold, and Elf-a can get 1 in 2.
(That works out to over 24 hours to hit Tired.)
Merge pull request #5542 from KA101/sleep-state

Less-sleep mutations