[0060] Backported conditions data and gossip data from TBC-DB

BACKUP YOUR DATA BEFORE UPDATING

* Thanks to evil-at-wow for the conditions data backported from TBC-DB (TBC-DB original data by X-Savior)
* Reconverted conditions for classic-only data
* Backported all gossip data from TBC-DB tables: 'gossip_menu', 'gossip_menu__option', 'db_script_string',
  'npc_text', 'dbscript_on_gossip'
* Fixed a few errors in backported data (mainly same content with different IDs)
* Updated 'npc_option_npcflag' from backported data according to what classic core expects
  Note: the difference of behavior between the two cores might be investigated as the GOSSIP enum
  data are the same in classic and TBC
* Removed many of TBC and WotLK data from backported content where gossip menu or conditions
  were related to creature, item, quest, spell, skill, level introduced in TBC/WotLK (data not
  clearly related to TBC or WotLK were left)