Core/Instances: Fix Instance binding

Fix players not being bound to instance if the group was disbanded before killing any boss.
Fixes #437

src/server/game/Groups/Group.cpp

@@ -1960,7 +1960,7 @@ void Group::ResetInstances(uint8 method, bool isRaid, Player* SendMsgTo)
         if (isEmpty || method == INSTANCE_RESET_GROUP_DISBAND || method == INSTANCE_RESET_CHANGE_DIFFICULTY)
         {
             // do not reset the instance, just unbind if others are permanently bound to it
-            if (instanceSave->CanReset())
+            if (isEmpty && instanceSave->CanReset())
                 instanceSave->DeleteFromDB();
             else
             {

src/server/game/Instances/InstanceSaveMgr.cpp

@@ -161,6 +161,12 @@ void InstanceSaveManager::RemoveInstanceSave(uint32 InstanceId)
     }
 }
 
+void InstanceSaveManager::UnloadInstanceSave(uint32 InstanceId)
+{
+    if (InstanceSave* save = GetInstanceSave(InstanceId))
+        save->UnloadIfEmpty();
+}
+
 InstanceSave::InstanceSave(uint16 MapId, uint32 InstanceId, Difficulty difficulty, time_t resetTime, bool canReset)
 : m_resetTime(resetTime), m_instanceid(InstanceId), m_mapid(MapId),
   m_difficulty(difficulty), m_canReset(canReset), m_toDelete(false) { }
@@ -232,6 +238,11 @@ bool InstanceSave::UnloadIfEmpty()
 {
     if (m_playerList.empty() && m_groupList.empty())
     {
+        // don't remove the save if there are still players inside the map
+        if (Map* map = sMapMgr->FindMap(GetMapId(), GetInstanceId()))
+            if (map->HavePlayers())
+                return true;
+
         if (!sInstanceSaveMgr->lock_instLists)
             sInstanceSaveMgr->RemoveInstanceSave(GetInstanceId());
 

src/server/game/Instances/InstanceSaveMgr.h

@@ -195,6 +195,7 @@ class InstanceSaveManager
         InstanceSave* AddInstanceSave(uint32 mapId, uint32 instanceId, Difficulty difficulty, time_t resetTime,
             bool canReset, bool load = false);
         void RemoveInstanceSave(uint32 InstanceId);
+        void UnloadInstanceSave(uint32 InstanceId);
         static void DeleteInstanceFromDB(uint32 instanceid);
 
         InstanceSave* GetInstanceSave(uint32 InstanceId);

src/server/game/Maps/Map.cpp

@@ -2863,6 +2863,7 @@ void InstanceMap::RemovePlayerFromMap(Player* player, bool remove)
     Map::RemovePlayerFromMap(player, remove);
     // for normal instances schedule the reset after all players have left
     SetResetSchedule(true);
+    sInstanceSaveMgr->UnloadInstanceSave(GetInstanceId());
 }
 
 void InstanceMap::CreateInstanceData(bool load)