[ticket/12699] Add tab key to keymap

PHPBB3-12699
[ticket/12699] Replace magic numbers for the TAB and for ENTER keydown

Replaced the magic numbers 9 and 13 in the keydown for the text editor
with constants in the existing keymap for phpBB.

PHPBB3-12699
[ticket/12705] Break calling make_clickable with a different server_url

PHPBB3-12705
[ticket/12705] Store the regular expression matches based on server_url

PHPBB3-12705
Merge pull request #2588 from nickvergessen/ticket/12705

Ticket/12705 Fix make_clickable when called with different server_urls
Merge pull request #2610 from brunoais/ticket/12699

[Ticket/12699] Remove magic numbers in the message textarea keydown callback

* brunoais/ticket/12699:
  [ticket/12699] Replace magic numbers for the TAB and for ENTER keydown
  [ticket/12699] Add tab key to keymap