DB/Spells: Cleaned playercreateinfo_spell_custom table and added WoTLK class spells only

Current playercreateinfo_spell_custom table has very weird spells in it. I emptied table, created new character for each class, logon each class, learned every spell from trainer and then added rest spells from quests (for example, hunters' Tame Beast). After that I did a PHP script to get character's spells from character_spell table and insert them into playercreateinfo_spell_custom table.

This has all trainer spells and quest spells (if any) for 3.3.5!

Fixes #13509
Closes #13516
DB/Quest: Rallying the Troops
Core/Commands: implement .pvpstats command

Shows number of battleground victories in the last 7 days

Closes #13460
Scripts/Commands: mod xp command

Closes #13476
Merge branch '3.3.5' of https://github.com/TrinityCore/TrinityCore into ghbb