Chair plane fix (and maybe fixes the disappearing humans, too)

code/datums/mutable_appearance.dm

@@ -5,11 +5,12 @@
 // Mutable appearances are children of images, just so you know.
 
 // Helper similar to image()
-/proc/mutable_appearance(icon, icon_state = "", layer = FLOAT_LAYER)
+/proc/mutable_appearance(icon, icon_state = "", layer = FLOAT_LAYER, plane = FLOAT_PLANE)
 	var/mutable_appearance/MA = new()
 	MA.icon = icon
 	MA.icon_state = icon_state
 	MA.layer = layer
+	MA.plane = plane
 	return MA
 
 /mutable_appearance/clean

code/game/objects/structures/stool_bed_chair_nest/chairs.dm

@@ -80,7 +80,7 @@
 
 /obj/structure/chair/proc/handle_layer()
 	if(buckled_mob && dir == NORTH)
-		layer = FLY_LAYER
+		layer = ABOVE_MOB_LAYER
 	else
 		layer = OBJ_LAYER