Traitor objective picking error fix, thanks to @thvortex.

Original Message:

Hopefully fixes #58 Traitor objective errors
I think the issue is in /datum/objective/steal/reagent not having a
"weight = " like any of the other steal objectives.

GenerateTheft() will use the "weight" var and not the "get_weight" proc
when building its list, but the default weight defined in /datum/objective
is INFINITY. PickObjectiveFromList() will then call pickweight() which
does a sum of all weights stored in the list followed by <= comparisons of
the total. Perhaps the total integer var wraps around into negative
values.

I have no idea if INFINITY is actually MAXINT, or either of the positive
or negative floating point infinities.

code/game/gamemodes/newobjective.dm

@@ -1086,6 +1086,7 @@ datum
 
 
 			reagent
+				weight = 20
 				var/target_name
 				New(var/text,var/joba)
 					..()