First attempt at smoker addition.
Finished added functional smoker zombies, fixed smoke move related bugs, added no_breathe tag for monsters

Specifically, many fields reduced a monster's speed, rather than a monsters move. This was changed, and smoke fields (and other gas fields) no longer slow monsters that don't breathe at all. Many monsters have had the MF_NO_BREATHE flag added to them - this may be scaled back later.
Fixed bug where fields did not conceal monsters.
Merge branch 'master' of https://github.com/GlyphGryph/Cataclysm-DDA

Conflicts:
	monattack.h