[ticket/11454] Correct jabber global available check

Copied from msg_jabber()

PBPBB3-11454
[ticket/11454] Add messenger function set_addresses

Automatically fills to/im from a user row

Send messenger the Jabber address if using Jabber notifications

PHPBB3-11454
[ticket/11454] Use set_addresses in other applicable areas

This should fix some other bugs that may not have yet been recognized--some
areas only set to(), but sent according to user_notify_type, which is not
necessarily email.

PHPBB3-11454
[ticket/11454] Check if the fields are set

PHPBB3-11454
Merge pull request #1367 from EXreaction/ticket/11454

Ticket/11454 - Jabber notifications are not working at all