New Perl/Lua buff functionality.

- Mob::FindBuffBySlot(slot)
	This allows you to find buffs by a specific slot.
	Example: https://i.imgur.com/VG68cxs.png
	Perl Example: https://pastebin.com/8HvMAC4h

- Mob::BuffCount()
	This will find the active number of buffs an NPC/client has.
	Example: https://i.imgur.com/jrLRBwV.png
	Perl Example: https://pastebin.com/Wmg16wwp

zone/lua_mob.h

@@ -82,6 +82,8 @@ public:
 	bool IsInvisible(Lua_Mob other);
     void SetInvisible(int state);
 	bool FindBuff(int spell_id);
+	uint16 FindBuffBySlot(int slot);
+	uint32 BuffCount();
     bool FindType(int type);
 	bool FindType(int type, bool offensive);
 	bool FindType(int type, bool offensive, int threshold);