fire update

enabled fire to destroy floors and objects
also tweaked the behaviour of glass to enable glasslocks against fire
also made fire extingiushers stop being useless

code/game/objects/effects/decals/Cleanable/scorchmark.dm

@@ -0,0 +1,15 @@
+obj/effect/decal/cleanable/scorchmark
+	//this is used as an additional visual result of fire and as a reagent holder for fuel created by burning of turfs and items.
+	icon = 'icons/effects/scorchmark.dmi'
+	name = "Soot"
+	icon_state = "1"
+	layer = TURF_LAYER+0.1
+	anchored = 1
+	var/amount = 0 //starts always empty and is filled by procs called by fire
+
+	New(newLoc,start_amount=0)
+		..()
+
+		icon_state = pick("1","2","3","4","5","6","7","8","9")
+		dir = pick(cardinal)
+		amount = start_amount