Core/Players: Fixed melee damage
Core/Items: Added item level caps
Define some opcodes
Core/Battle.net: Fixed client crashes happening when reconnecting too soon after being kicked
Core/DBLayer: Removed a few old authserver prepared statements
Dep/zlib: Update zlib from version 1.2.7 to 1.2.8

"Version 1.2.8 fixes a very rare bug in decompression. All users are encouraged to upgrade immediately. Version 1.2.8 also has these improvements:
Add new inflateGetDictionary() function
Fix bug where gzopen() immediately followed by gzclose() would write an empty file instead of an empty gzip stream.
Fix bug in gzclose() when gzwrite() runs out of memory"
Core/DataStores: Implemented loading hotfixes database into DB2Storage
Core/DataStores: Implemented loading locale strings from database to DB2Storage
Scripts/Nexus: rewritten instance script

(cherry picked from commit f743fb3e43036bdfd4e6b96dff1a82c19e3faa59)
Scripts/Nexus: Implement Grand Magus Telestra's seasonal costume

Closes #13643

(cherry picked from commit e2f7b91298d6588c062db2d1132a62ddd8a4437a)
Core/Items: Fix signed/unsigned mismatch warnings
Core/PetitionsHandler: Move charter costs to config

(cherry picked from commit 0c1d3aa344921b324b7bf5e164a228a0d2a1aa70)

Conflicts:
	src/server/game/World/World.h
Core/DataStores: Moved broadcast_text handling to DB2Storage
Merge pull request #13751 from Unholychick/6.0.3

Core/Scripts: Add new SpellScript hook
Merge pull request #13744 from Golrag/Opcodes

Core/Opcodes: Add some opcodes
Core/DataStores: Added DB2Manager

* Moved DB2 helpers to new class
* Moved hotfix data to hotfixes database and core management functions to DB2Manager class
* Updated HotfixNotifyBlob packet
DB/Quests: Moved quest visual effects to their own table
Scripts/Naxxramas: Add script support for quarter teleporters and spawn missing ones

Updates #13255

(cherry picked from commit aff5229cd1777581bd85079d064037a57bf17799)
DB/Quests: Splitted quest_template into different tables
SQLs: Replace placehold variable by default world db name

Travis tests SQL imports and it would fail otherwise.

Do not forget to change the variable to your world database name (if different from 'world') in the file 2014_12_25_00_hotfixes_locale_broadcast_text.sql