[DONE - Please Review] Change trap detection dynamics.

Re: Issue #7800

Traps can be found by wandering around or standing still (with the `.` key).

Candidate search radius increased to 11 squares.

Detection is combination of perception, tiredness, stimulus, luck, distance from trap, and trap visibility.

Traps must be detected before being known and seen.

Detection numbers probably need to be tweaked, but in my tests this seems fun despite my earlier (and overblown) apprehension.

I'm anti-social and rarely go on the forums. If someone has already proposed something better there, just delete this branch.
NOPE.  This gets rid of stashes...and corpses, lava rifts, helicrashes, artifact sites, portals, etc.  I'm not merging that.