[ticket/12604] Fix wrong padding when no notifications

Added a class to the <li> when the <li> represents that there's no
notifications (no_notifications) and
Added a CSS rule that matches the change to the HTML source for when
there's no notifications.

PHPBB3-12604
Merge pull request #2506 from brunoais/ticket/12604

[ticket/12604] Fix wrong padding when no notifications

* brunoais/ticket/12604:
  [ticket/12604] Fix wrong padding when no notifications
[ticket/12614] Make the post buttons always visible.

PHPBB3-12614
Merge pull request #2513 from prototech/ticket/12614

[ticket/12614] Make the post buttons always visible.

* prototech/ticket/12614:
  [ticket/12614] Make the post buttons always visible.
[ticket/12508] Remove extension manager from finder

PHPBB3-12508
[ticket/12508] Fix usages of the finder

PHPBB3-12508
[ticket/12508] Move \phpbb\extension\finder to \phpbb\finder

PHPBB3-12508
[ticket/12508] Fix class doc block

PHPBB3-12508
[ticket/12508] Only take a list of names for set_extensions()

PHPBB3-12508
[ticket/12508] Add a unit test for set_extensions()

PHPBB3-12508
[ticket/12508] Add new line to mark the sections more clearly

PHPBB3-12508