Processor-driven effects system & Minor Lighting Performance Tweaks (#1697)

Adds a new process-based effects system with the goal of reducing insane lag from sparks.
Currently only supports sparks, but should be easily extendable to other types of effects.
Also fixes a bug with airlocks where the light from bolts wasn't updating.

Refactors bears slightly to reduce duplicated code & pointless spark object creation and destruction.
Lighting profiler will now log /turf locations & names correctly.
Doors will no longer trigger way more visibility checks than they need to.

code/modules/effects/visual_effect.dm

@@ -0,0 +1,38 @@
+/obj/visual_effect
+	name = "effect"
+	anchored = 1
+	simulated = 0
+	mouse_opacity = 0
+	var/life_ticks			// How many ticks this effect will life before it stops processing.
+	var/life_ticks_max		// The high limit for the random tick picker.
+	var/life_ticks_min		// The low limit for the random tick picker.
+	var/live_icon_state		// The icon-state to use when this object is shown to the user.
+
+/obj/visual_effect/New(var/life_min = 3 SECONDS, var/life_max = 5 SECONDS)
+	..()
+	life_ticks_min = life_min
+	life_ticks_max = life_max
+	life_ticks = rand(life_ticks_min, life_ticks_max)
+
+// Called when the visual_effect is manifested.
+/obj/visual_effect/proc/start()
+	if (live_icon_state)
+		icon_state = live_icon_state
+
+// Called every effects processor tick. Return value determines what the process does to this object.
+/obj/visual_effect/proc/tick()
+	if (!life_ticks)	
+		return EFFECT_DESTROY
+
+	life_ticks--
+	return EFFECT_CONTINUE
+
+// Called just before the visual_effect is returned to the pool.
+/obj/visual_effect/proc/end()
+	loc = null
+	if (live_icon_state)
+		icon_state = null
+
+/obj/visual_effect/Destroy()
+	// ¯\_(ツ)_/¯
+	// This runtimes in expansions.dm if ..() is called.