Fix smoke (#1996)

changes:

Smoke no longer leaves mysterious patches of darkness.
Smoke now uses client-side animations instead of while loops.
Fixes #1985.

code/game/objects/effects/chem/chemsmoke.dm

@@ -24,20 +24,11 @@
 	pixel_x = -32 + rand(-8, 8)
 	pixel_y = -32 + rand(-8, 8)
 
-	//switching opacity on after the smoke has spawned, and then turning it off before it is deleted results in cleaner
-	//lighting and view range updates (Is this still true with the new lighting system?)
-	set_opacity(1)
-
 	//float over to our destination, if we have one
 	destination = dest_turf
 	if(destination)
 		walk_to(src, destination)
 
-/obj/effect/effect/smoke/chem/Destroy()
-	set_opacity(0)
-	fadeOut()
-	..()
-
 /obj/effect/effect/smoke/chem/Move()
 	var/list/oldlocs = view(1, src)
 	. = ..()
@@ -61,16 +52,6 @@
 			if(!istype(AM, /obj/effect/effect/smoke/chem))
 				reagents.splash(AM, splash_amount, copy = 1)
 
-// Fades out the smoke smoothly using it's alpha variable.
-/obj/effect/effect/smoke/chem/proc/fadeOut(var/frames = 16)
-	if(!alpha) return //already transparent
-
-	frames = max(frames, 1) //We will just assume that by 0 frames, the coder meant "during one frame".
-	var/alpha_step = round(alpha / frames)
-	while(alpha > 0)
-		alpha = max(0, alpha - alpha_step)
-		sleep(world.tick_lag)
-
 /////////////////////////////////////////////
 // Chem Smoke Effect System
 /////////////////////////////////////////////

code/game/objects/effects/effect_system.dm

@@ -113,7 +113,18 @@ steam.start() -- spawns the effect
 	if (duration)
 		time_to_live = duration
 	spawn (time_to_live)
-		qdel(src)
+		kill()
+
+/obj/effect/effect/smoke/proc/kill()
+	set waitfor = FALSE
+	animate(src, alpha = 0, time = 2 SECONDS, easing = QUAD_EASING)
+	set_opacity(FALSE)
+
+	var/turf/T = get_turf(src)
+	if (T)
+		T.force_update_lights()	// I hate it, but nothing else seems to work.
+	
+	QDEL_IN(src, 2 SECONDS)
 
 /obj/effect/effect/smoke/Crossed(mob/living/carbon/M as mob )
 	..()
@@ -271,8 +282,8 @@ steam.start() -- spawns the effect
 				sleep(10)
 				step(smoke,direction)
 			spawn(smoke.time_to_live*0.75+rand(10,30))
-				if (smoke) qdel(smoke)
 				src.total_smoke--
+				qdel(smoke)
 
 
 /datum/effect/effect/system/smoke_spread/bad