Light floor added

For non-coders:
- Added floor lights
- To build: Use wire on glass, use metal on the assembly you get, use it on a plating. To fix flickering or broken tiles, use a lightbulb on them.
- To deconstruct: Crowbar on floor to remove it, crowbar on light tile to remove metal, wirecutters to separate the wire from the glass.
- Click on tile with an empty hand to turn it on/off

For coders:
- The turf system has been rewritten to contain a tile variable which defines what kind of turf it is. The 'intact' var can no longer be used to determine if the turf is a steel floor. Intact only tells if wires and pipes are to be hidden (for hide() procs)
- Use is_plating(), is_steel_floor() and is_light_floor() to determine the floor type.
- Use make_plating(), make_steel_floor() and make_light_floor() to do this. They take the floor tile by default as a parameter, if none is given they will make one themselves.

Credits for the sprites go to Hempuli, used with permission.

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@1513 316c924e-a436-60f5-8080-3fe189b3f50e

code/game/objects/items/clothing.dm

@@ -960,7 +960,7 @@ NINJA MASK
 	var/mob/living/carbon/human/U = usr
 	if(candrain&&!draining)
 		var/turf/T = U.loc
-		if(isturf(T) && !T.intact)
+		if(isturf(T) && T.is_plating())
 			attached = locate() in T
 			if(!attached)
 				U << "\red Warning: no exposed cable available."