-Added constructable solar arrays.

-Added a solar pack crate to order.
-Machines that have a use_power of 0 will no longer be turned off due to lack of power in the area.
-Fixed a bug with the solar computer not reconnecting to the powernet when dismantled and remantled.
-Increased the cap of crates to 30.
-Some performance tweaks.
-Some standardization.
-All objects of type /obj/machinery/power will try to disconnect from the powernet before deleting, this will help reduce the node list size.
-Added a heat_proof variable for doors. It will effect glass airlocks and it'll determine whether they can block heat or not. Research glass airlocks will always have it enabled.

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@5344 316c924e-a436-60f5-8080-3fe189b3f50e

code/modules/power/power.dm

@@ -9,6 +9,10 @@
 	idle_power_usage = 0
 	active_power_usage = 0
 
+/obj/machinery/power/Del()
+	disconnect_from_network()
+	..()
+
 // common helper procs for all power machines
 /obj/machinery/power/proc/add_avail(var/amount)
 	if(powernet)
@@ -38,6 +42,9 @@
 	if(!src.loc)
 		return 0
 
+	if(!use_power)
+		return 1
+
 	var/area/A = src.loc.loc		// make sure it's in an area
 	if(!A || !isarea(A) || !A.master)
 		return 0					// if not, then not powered