[ticket/12990] Use the full services name for the notification's types

PHPBB3-12990
[ticket/12990] Fix unit tests

PHPBB3-12990
[ticket/12990] Use protected instead of private

PHPBB3-12990
[ticket/12998] Fix use of $lang in mcp_warn.php

PHPBB3-12998
[ticket/12994] Add core event to viewtopic.php before sending vars to template

Add core event to viewtopic.php before sending vars to template
to allow extensions performing additional actions/modifying data first.

PHPBB3-12994
Merge pull request #2889 from rxu/ticket/12994

[ticket/12994] Add core event to viewtopic.php before sending vars to template
Merge pull request #2885 from Nicofuma/ticket/12990

[ticket/12990] Use the full services name for the notification's types