[7393] Implement access to client side holiday ids. Author: VladimirMangos

* src/game/GameEvent.* renamed to src/game/GameEventMgr.* for consistence
    * `game_event` now have new `holiday` field for store client side holiday id associated with game event
    * Added new enum HolidayIds with existed at this moment holiday ids.
    * New function "bool IsHolidayActive(HolidayIds id)" added accessabel from scripts for active holidays check.

--HG--
branch : trunk

src/game/SharedDefines.h

@@ -1672,6 +1672,31 @@ enum CreatureEliteType
     CREATURE_UNKNOWN               = 5                      // found in 2.2.3 for 2 mobs
 };
 
+// values based at Holidays.dbc
+enum HolidayIds
+{
+    HOLIDAY_FIREWORKS_SPECTACULAR    = 62,
+    HOLIDAY_FEAST_OF_WINTER_VEIL     = 141,
+    HOLIDAY_NOBLEGARDEN              = 181,
+    HOLIDAY_CHILDRENS_WEEK           = 201,
+    HOLIDAY_CALL_TO_ARMS_AV          = 283,
+    HOLIDAY_CALL_TO_ARMS_WG          = 284,
+    HOLIDAY_CALL_TO_ARMS_AB          = 285,
+    HOLIDAY_FISHING_EXTRAVAGANZA     = 301,
+    HOLIDAY_HARVEST_FESTIVAL         = 321,
+    HOLIDAY_HALLOWS_END              = 324,
+    HOLIDAY_LUNAR_FESTIVAL           = 327,
+    HOLIDAY_LOVE_IS_IN_THE_AIR       = 335,
+    HOLIDAY_FIRE_FESTIVAL            = 341,
+    HOLIDAY_CALL_TO_ARMS_ES          = 353,
+    HOLIDAY_BREWFEST                 = 372,
+    HOLIDAY_DARKMOON_FAIRE_ELWYNN    = 374,
+    HOLIDAY_DARKMOON_FAIRE_THUNDER   = 375,
+    HOLIDAY_DARKMOON_FAIRE_SHATTRATH = 376,
+    HOLIDAY_CALL_TO_ARMS_SA          = 400,
+    HOLIDAY_WOTLK_LAUNCH             = 406
+};
+
 // values based at QuestInfo.dbc
 enum QuestTypes
 {