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
Variable sort-out

Gets rid of one reference error and uses the unused variable.
Merge branch 'fix-bionic-removal-bug' of https://github.com/BevapDin/Cataclysm-DDA into merge
Merge branch 'no-footsteps' of https://github.com/BevapDin/Cataclysm-DDA into merge