Shieldgens:

-code cleanup and some improvements by Barhandar;
-more code cleanup;
-fixed availiable power colculation;
And some insignificant changes.


git-svn-id: http://tgstation13.googlecode.com/svn/trunk@730 316c924e-a436-60f5-8080-3fe189b3f50e

code/modules/power/apc.dm

@@ -162,7 +162,7 @@
 		else
 			if (stat & MAINT)
 				usr << "The cover is closed. Something wrong with it: it's doesn't work."
-			else if (emagged || malfhack)
+			else if (malfhack)
 				usr << "The cover is broken. It's may be hard to force it open."
 			else
 				usr << "The cover is closed."

code/modules/power/power.dm

@@ -370,7 +370,7 @@
 	
 /turf/proc/get_cable_node()
 	if(!istype(src, /turf/simulated/floor))
-		return
+		return null
 	for(var/obj/cable/C in src)
 		if(C.d1 == 0)
 			return C