[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/Nanos.hpp

@@ -3,6 +3,7 @@
 #include "core/Core.hpp"
 
 #include "Player.hpp"
+#include "Abilities.hpp"
 
 #include <map>
 
@@ -25,4 +26,5 @@ namespace Nanos {
     void summonNano(CNSocket* sock, int slot, bool silent = false);
     int nanoStyle(int nanoID);
     bool getNanoBoost(Player* plr);
+    std::vector<ICombatant*> applyNanoBuff(SkillData* skill, Player* plr);
 }