The iconfixongler (#2299)

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## About The Pull Request
Fixes a bunch of icon stuff (3 bugs introduced by update_appearance, 1
introduced by whitesands)
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## Why It's Good For The Game
Who's going trick or treating this year
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## Changelog

:cl:
fix: iv drip now has a sprite again
fix: shotgun drums now have a sprite again
fix: blood bank now has a sprite while filled
fix: layer manifolds now display inserted pipes properly again
/:cl:

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code/game/machinery/iv_drip.dm

@@ -31,7 +31,7 @@
 	if(attached)
 		icon_state = "[base_icon_state]_[mode ? "injecting" : "donating"]"
 	else
-		icon_state = "[base_icon_state]_[mode ? "injecting" : "donating"]"
+		icon_state = "[base_icon_state]_[mode ? "injectidle" : "donateidle"]"
 	return ..()
 
 /obj/machinery/iv_drip/update_overlays()

code/modules/atmospherics/machinery/pipes/layermanifold.dm

@@ -43,7 +43,6 @@
 	return front_nodes + back_nodes + nodes
 
 /obj/machinery/atmospherics/pipe/layer_manifold/update_layer()
-	cut_overlays()
 	layer = initial(layer) + (PIPING_LAYER_MAX * PIPING_LAYER_LCHANGE)	//This is above everything else.
 
 /obj/machinery/atmospherics/pipe/layer_manifold/update_overlays()

code/modules/projectiles/boxes_magazines/external/shotgun.dm

@@ -2,6 +2,7 @@
 	name = "shotgun drum magazine (12g buckshot)"
 	desc = "A bulky drum magazine for shotguns."
 	icon_state = "m12gb"
+	base_icon_state = "m12gb"
 	ammo_type = /obj/item/ammo_casing/shotgun/buckshot
 	caliber = "12ga"
 	max_ammo = 8