Basically ripped over /tg/'s powernet and cable code into our own codebase.

Keeps Z-level code as it was.
Modifies/restores powernet procs as necessary to match our own implementation changes.

code/modules/mining/coins.dm

@@ -63,7 +63,7 @@
 
 		var/obj/item/stack/cable_coil/CC = new/obj/item/stack/cable_coil(user.loc)
 		CC.amount = 1
-		CC.updateicon()
+		CC.update_icon()
 		overlays = list()
 		string_attached = null
 		user << "\blue You detach the string from the coin."