Fix some issues with SSplants processing (#3417)

Fixes some issues where plants would not get removed from their processing list properly.

code/modules/hydroponics/spreading/spreading.dm

@@ -67,11 +67,10 @@
 	var/last_biolum = null
 
 /obj/effect/plant/Destroy()
-	if(SSplants)
-		STOP_PROCESSING(SSplants, src)
+	SSplants.remove_plant(src)
 	for(var/obj/effect/plant/neighbor in range(1,src))
 		if (!QDELETED(neighbor))
-			START_PROCESSING(SSplants, neighbor)
+			SSplants.add_plant(neighbor)
 	return ..()
 	
 /obj/effect/plant/single
@@ -129,7 +128,7 @@
 /obj/effect/plant/proc/post_initialize()
 	set_dir(calc_dir())
 	update_icon()
-	START_PROCESSING(SSplants, src)
+	SSplants.add_plant(src)
 	// Some plants eat through plating.
 	if(islist(seed.chems) && !isnull(seed.chems["pacid"]))
 		var/turf/T = get_turf(src)
@@ -239,9 +238,9 @@
 /obj/effect/plant/attackby(var/obj/item/weapon/W, var/mob/user)
 
 	user.setClickCooldown(DEFAULT_ATTACK_COOLDOWN)
-	START_PROCESSING(SSplants, src)
+	SSplants.add_plant(src)
 
-	if(istype(W, /obj/item/weapon/wirecutters) || istype(W, /obj/item/weapon/scalpel))
+	if(iswirecutter(W) || istype(W, /obj/item/weapon/scalpel))
 		if(sampled)
 			user << "<span class='warning'>\The [src] has already been sampled recently.</span>"
 			return

code/modules/hydroponics/spreading/spreading_growth.dm

@@ -23,6 +23,10 @@
 		if(!Adjacent(floor) || !floor.Enter(src))
 			continue
 		neighbors |= floor
+
+	if (neighbors.len)
+		SSplants.add_plant(src)
+
 	// Update all of our friends.
 	var/turf/T = get_turf(src)
 	for(var/obj/effect/plant/neighbor in range(1,src))
@@ -82,8 +86,8 @@
 
 	// We shouldn't have spawned if the controller doesn't exist.
 	check_health()
-	if(neighbors.len || health != max_health)
-		START_PROCESSING(SSplants, src)
+	if(neighbors.len || health != max_health || buckled_mob)
+		SSplants.add_plant(src)
 
 /obj/effect/plant/proc/do_spread(spread_chance, max_spread)
 	for(var/i in 1 to max_spread)
@@ -113,7 +117,7 @@
 			continue
 		for(var/obj/effect/plant/neighbor in check_turf.contents)
 			neighbor.neighbors |= check_turf
-			START_PROCESSING(SSplants, neighbor)
+			SSplants.add_plant(neighbor)
 
 	QDEL_IN(src, 1)