Lots of bugs fixed for advance diseases.

Fixed advance diseases using the same reference in mobs.
Fixed advance diseases referencing other advance diseases' symptoms, instead of just copying it.

I tested it more thoroughly this time and I can't find any issues but if you do please add them to the bug tracker and or contact me on #coderbus.

Added a new reaction which will remove symptoms from a disease. Needs blood and synaptizine.
Added a new symptom, shivering will make you cold.

Tweaked and balanced some symptoms.

Removed the "flex" emote that hulks will do randomly.
Reduced the change to speak for hulks and brain damaged mobs. ( 7% -> 3% chance)

Please let me know if anything is out of place or wrong.

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@5048 316c924e-a436-60f5-8080-3fe189b3f50e

code/__HELPERS/lists.dm

@@ -304,9 +304,4 @@ proc/listclearnulls(list/list)
 			if(bitfield & bit)
 				r += bit
 
-	return r
-
-/proc/safe_pick_list(var/list/L)
-	if(L && L.len)
-		return pick(L)
-	return null
+	return r