Fixed Shiv.

* Now it does weapon dmg and adds a combo point even without poison (yes, that's blizzlike).
* Poisons from Shiv cannot crit.
* No more double poison procs.

--HG--
branch : trunk

src/server/game/Entities/Player/Player.cpp

@@ -7807,6 +7807,10 @@ void Player::CastItemCombatSpell(Unit *target, WeaponAttackType attType, uint32
 
             // Apply spell mods
             ApplySpellMod(pEnchant->spellid[s],SPELLMOD_CHANCE_OF_SUCCESS,chance);
+            
+            // Shiv has 100% chance to apply the poison
+            if (FindCurrentSpellBySpellId(5938))
+                chance = 100.0f;
 
             if (roll_chance_f(chance))
             {