[refactor] New buff framework (player implementation)

Get rid of `iConditionBitFlag` in favor of a system of individual buff
objects that get composited to a bitflag on-the-fly.
Buff objects can have callbacks for application, expiration, and tick,
making them pretty flexible. Scripting languages can eventually use
these for custom behavior, too.

TODO:
- Get rid of bitflag in BaseNPC
- Apply buffs from passive nano powers
- Apply buffs from active nano powers
- Move eggs to new system
- ???

src/Eggs.hpp

@@ -10,12 +10,10 @@ struct EggType {
 };
 
 namespace Eggs {
-    extern std::map<std::pair<CNSocket*, int32_t>, time_t> EggBuffs;
     extern std::unordered_map<int, EggType> EggTypes;
 
     void init();
 
-    /// returns -1 on fail
-    int eggBuffPlayer(CNSocket* sock, int skillId, int eggId, int duration);
+    void eggBuffPlayer(CNSocket* sock, int skillId, int eggId, int duration);
     void npcDataToEggData(int x, int y, int z, sNPCAppearanceData* npc, sShinyAppearanceData* egg);
 }