Fixes engie ERT's infinitely-duplicable materials

Also removes the (worthlessly broken) full-stack subtypes added
specifically for them.

code/game/objects/items/stacks/sheets/glass.dm

@@ -31,10 +31,6 @@
 	g_amt = 0
 	created_window = /obj/structure/window/basic
 
-/obj/item/stack/sheet/glass/full/New()
-	..()
-	amount = 50
-
 /obj/item/stack/sheet/glass/attack_self(mob/user as mob)
 	construct_window(user)
 

code/game/objects/items/stacks/sheets/sheet_types.dm

@@ -90,10 +90,6 @@ var/global/list/datum/stack_recipe/metal_recipes = list ( \
 	flags = CONDUCT
 	origin_tech = "materials=1"
 
-/obj/item/stack/sheet/metal/full/New()
-	..()
-	amount = 50
-
 /obj/item/stack/sheet/metal/cyborg
 	name = "metal"
 	desc = "Sheets made out off metal. It has been dubbed Metal Sheets."
@@ -136,10 +132,6 @@ var/global/list/datum/stack_recipe/plasteel_recipes = list ( \
 	recipes = plasteel_recipes
 	return ..()
 
-/obj/item/stack/sheet/plasteel/full/New(var/loc, var/amount=null)
-	amount = 50
-	..(loc, amount)
-
 /*
  * Wood
  */