atmos: fix everlasting fires

Fires were checking against a non-reduced air sample for existance, so
the reduced sample wasn't working in zburn when it failed the check.
Also fixed volatilefuel not being scaled in the phoron reagent.

Signed-off-by: Mloc-Argent <colmohici@gmail.com>

Conflicts:
	code/ZAS/Fire.dm
	code/modules/reagents/Chemistry-Reagents.dm
Makes forks usable.

Conflicts:
	code/game/objects/items/weapons/kitchen.dm
	icons/obj/kitchen.dmi
Merge branch 'master' of https://github.com/ZomgPonies/Paradise