Conveyor movement refactor/fix (#26408)

* Refactors conveyor movement

* Fixes effects being affected by conveyors

* Fixes jetpacks not stopping conveyors

* Fixes /mob/dead being affected by conveyors

* Fixes butterflys being affected by conveyors

code/modules/mob/dead/dead.dm

@@ -10,3 +10,6 @@
 
 /mob/dead/gib()		//ghosts can't be gibbed.
 	return
+
+/mob/dead/ConveyorMove()	//lol
+	return

code/modules/mob/living/living.dm

@@ -923,3 +923,8 @@
 	if(riding_datum)
 		riding_datum.handle_vehicle_offsets()
 		riding_datum.handle_vehicle_layer()
+
+/mob/living/ConveyorMove()
+	if((movement_type & FLYING) && !stat)
+		return
+	..()

code/modules/mob/living/simple_animal/friendly/butterfly.dm

@@ -27,4 +27,4 @@
 /mob/living/simple_animal/butterfly/Initialize()
 	..()
 	var/newcolor = rgb(rand(0, 255), rand(0, 255), rand(0, 255))
-	add_atom_colour(newcolor, FIXED_COLOUR_PRIORITY)
+	add_atom_colour(newcolor, FIXED_COLOUR_PRIORITY)

code/modules/recycling/conveyor2.dm

@@ -108,10 +108,8 @@
 	affecting = loc.contents - src		// moved items will be all in loc
 	sleep(1)
 	for(var/atom/movable/A in affecting)
-		if(!A.anchored)
-			if(A.loc == src.loc) // prevents the object from being affected if it's not currently here.
-				step(A,movedir)
-		CHECK_TICK
+		if(A.loc == loc)
+			A.ConveyorMove(movedir)
 
 // attack with item, place item on conveyor
 /obj/machinery/conveyor/attackby(obj/item/I, mob/user, params)