You can no longer transition off the away mission Z level (so people don't randomly end up at telecomms after running off the edge of a tundra or something)

Alien weeds now die in one hit to a welding tool, and 6 from a extinguisher. You can plant like a billion of them for no cost, they shouldn't take four hits of a welding tool to clear.

Added the black crab sprites for HG

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@4693 316c924e-a436-60f5-8080-3fe189b3f50e

code/game/objects/effects/aliens.dm

@@ -169,7 +169,7 @@
 
 	anchored = 1
 	density = 0
-	var/health = 50
+	var/health = 15
 
 	node
 		icon_state = "weednode"

code/game/turfs/space/space.dm

@@ -70,6 +70,7 @@
 
 		// Okay, so let's make it so that people can travel z levels but not nuke disks!
 		// if(ticker.mode.name == "nuclear emergency")	return
+		if(A.z > 6) return
 		if (A.x <= TRANSITIONEDGE || A.x >= (world.maxx - TRANSITIONEDGE - 1) || A.y <= TRANSITIONEDGE || A.y >= (world.maxy - TRANSITIONEDGE - 1))
 			if(istype(A, /obj/effect/meteor)||istype(A, /obj/effect/space_dust))
 				del(A)