Change trap detection dynamics.

Traps now must be searched for. 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.

Numbers probably need to be tweaked, but in my tests this seems fun despite my earlier (and overblown) apprehension.
redundant is redundantly redundant.
Removing dead code.

Not sure if map_extra_chance was kept for reference, but it's dead Jim.
Trap search done on move.
insert some comment about juggalos, science, magnets, and magic.

Oh, and maths. Search math should actually search an area of 11.

And more comments for the why the math is the way it is in search_surroundings().
Incendiary grenade item & spawns
Explosion and incendiary field
Merge remote-tracking branch 'upstream/master' into its_a_trap
Turned off stashes/extras... i think.
Remove my ignorant comments, turn of just "stashes" not all the extras.

After fiddling with the numbers and trying out some calculations, I kept the weighted numbers as is and if stash was chosen, it acts as if no extra is chosen and falls through. This keeps all other extras appearing at the same quantity and frequency as they would appear now.
Merge remote-tracking branch 'upstream/master' into its_a_trap
Remove errant comment.
Fixes #7929

Makes tent and harmless traps work alike, and all traps get the pickup
item after disarming.
Merge pull request #8022 from John-Candlebury/pyromania!

Incendiary Grenades!
Variable sort-out

Gets rid of one reference error and uses the unused variable.
Merge pull request #8035 from KA101/buildfix

Variable sort-out
bionic removal: handle case when no item for the bionic exists.

Use item_controller instead of itypes map.
Check if item exists before getting it from the controller.
Remove the explicit check to player::bionics because that is done in player::has_bionic anyway.
Check the bionic id, instead of the bionic item id.

Fix some unrelated comparison warnings.
ignore footsteps from monsters when player is deaf
Incendiary grenade item & spawns
Explosion and incendiary field