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/power/terminal.dm

@@ -11,7 +11,6 @@
 	layer = TURF_LAYER
 	var/obj/machinery/power/master = null
 	anchored = 1
-	directwired = 0		// must have a cable on same turf connecting to terminal
 	layer = 2.6 // a bit above wires
 
 
@@ -21,6 +20,10 @@
 	if(level==1) hide(T.intact)
 	return
 
+/obj/machinery/power/terminal/Del()
+	if(master)
+		master.disconnect_terminal()
+	return ..()
 
 /obj/machinery/power/terminal/hide(var/i)
 	if(i)