Bugfixes + Damage Formula Adjustment

* Entering/exiting groups should apply/remove group buffs.
* Fixed issues with nanos losing all stamina from various revives/warp away.
* Heavily tweaked damage formula, nano types now boost/decrease damage.
* Weapons can consume battery returning extra damage, battery consumed depends on enemy level.

src/GroupManager.hpp

@@ -20,4 +20,6 @@ namespace GroupManager {
     void sendToGroup(Player* plr, void* buf, uint32_t type, size_t size);
     void groupTickInfo(Player* plr);
     void groupKickPlayer(Player* plr);
+    void groupUnbuff(Player* plr);
+    int getGroupFlags(Player* plr);
 }