Mining mechs, which currently only spawn in secret asteroid rooms, no longer have tracking beacons

Changes to windoors.
- Secure windoors now require 2 plasteel sheets instead of 4 rods
- Windoors and secure windoors have reduced health.

Added checks for proximity, canmove and death on:
- Library scanner
- Library computer
- Library public computer
- Bookcases (Fixes issue 564.)

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@3824 316c924e-a436-60f5-8080-3fe189b3f50e

code/game/objects/windoor_assembly.dm

@@ -107,9 +107,9 @@ obj/structure/windoor_assembly/Del()
 						src.name = "Windoor Assembly"
 
 			//Adding r-glass makes the assembly a secure windoor assembly. Step 2 (optional) complete.
-			else if(istype(W, /obj/item/stack/rods) && !secure)
-				var/obj/item/stack/rods/R = W
-				if(R.amount < 4)
+			else if(istype(W, /obj/item/stack/sheet/plasteel) && !secure)
+				var/obj/item/stack/sheet/plasteel/P = W
+				if(P.amount < 2)
 					user << "\red You need more rods to do this."
 					return
 				user << "\blue You start to reinforce the windoor with rods."
@@ -117,7 +117,7 @@ obj/structure/windoor_assembly/Del()
 				if(do_after(user,40))
 					if(!src) return
 
-					R.use(4)
+					P.use(2)
 					user << "\blue You reinforce the windoor."
 					src.secure = "secure_"
 					if(src.anchored)