Ports holomap blueprints from tg/vg.

Changes:
 - Clicking "view structural data" in the station blueprints menu will
   show you ghost images of where things like disposal pipes, wires,
   atmospherics pipes, and other power machinery are originally supposed
   to go. Note, this will show you the ghost images over turfs even if the
   machinery is destroyed.

code/modules/power/cable.dm

@@ -25,6 +25,7 @@ By design, d1 is the smallest direction and d2 is the highest
 /obj/structure/cable
 	level = 1
 	anchored =1
+	on_blueprints = TRUE
 	var/datum/powernet/powernet
 	name = "power cable"
 	desc = "A flexible superconducting cable for heavy-duty power transfer"

code/modules/power/power.dm

@@ -10,6 +10,7 @@
 	name = null
 	icon = 'icons/obj/power.dmi'
 	anchored = 1.0
+	on_blueprints = TRUE
 	var/datum/powernet/powernet = null
 	use_power = 0
 	idle_power_usage = 0