[ticket/12961] Add link in anti-spam ACP page to titania

PHPBB3-12961
[ticket/12961] Change url to https://www.phpbb.com/go/anti-spam/

PHPBB3-12961
[ticket/12961] Change url to anti-spam-ext

As per IRC suggestion

PHPBB3-12961
[ticket/12961] Refactor lang entry

PHPBB3-12961
[ticket/12961] Move link to language file

PHPBB3-12961
[ticket/12961] Add additional link to the KB

PHPBB3-12961
[ticket/12961] Remove target="_blank" and switch to <strong>

PHPBB3-12961
[ticket/12961] Fix missing phpBB.com

Don't know how that happened. Weird

PHPBB3-12961
[ticket/12961] Shorten ext-db link text

PHPBB3-12961
Merge pull request #2875 from PayBas/ticket/12961

[ticket/12961] Add link in anti-spam ACP page which links directly to captchas in titania

* PayBas/ticket/12961:
  [ticket/12961] Shorten ext-db link text
  [ticket/12961] Fix missing phpBB.com
  [ticket/12961] Remove target="_blank" and switch to <strong>
  [ticket/12961] Add additional link to the KB
  [ticket/12961] Move link to language file
  [ticket/12961] Refactor lang entry
  [ticket/12961] Change url to anti-spam-ext
  [ticket/12961] Change url to https://www.phpbb.com/go/anti-spam/
  [ticket/12961] Add link in anti-spam ACP page to titania