Ref link fixed, nickname fixed, several rewrites, TODOs.txt updated:

Ref link fixed, nickname fixed, several rewrites, TODOs.txt updated:
- Reflink should now work again with nicknames, rewritten to use
  NICKNAME_GET_NICK()
- Above function fixed (may be now better)
- Several rewrites of SQL_FETCHROW() to SQL_FETCHARRAY() (internal TODO)
- Several constants rewritten to $content (internal TODO)
- TODOs.txt updated