Separates the sharp flag into edge and sharp

Now weapons can properly cause cuts without necessarily having a greater
chance to remove limbs.

Also separates is_sharp, has_edge, and can_puncture.

code/game/objects/items/latexballoon.dm

@@ -44,5 +44,5 @@
 	return
 
 /obj/item/latexballon/attackby(obj/item/W as obj, mob/user as mob)
-	if (is_sharp(W))
+	if (can_puncture(W))
 		burst()