[ticket/12586] Use dot filter when trying to find available extensions

PHPBB3-12586
[ticket/12586] Limit depth to 2, we require vendor/extension/ext.php

PHPBB3-12586
Merge pull request #2491 from nickvergessen/ticket/12586

Ticket/12586 Filter files and depth when looking for extensions

* nickvergessen/ticket/12586:
  [ticket/12586] Limit depth to 2, we require vendor/extension/ext.php
  [ticket/12586] Use dot filter when trying to find available extensions
Merge pull request #2484 from Nicofuma/ticket/12576

[ticket/12576] Remove cron from common.php

* Nicofuma/ticket/12576:
  [ticket/12576] Retrieve the cron_manager in cron.php if needed
  [ticket/12576] Remove cron from common.php
Merge pull request #2465 from prototech/ticket/12549

[ticket/12549] Hide topic/forum list <dfn> tags in RTL languages.

* prototech/ticket/12549:
  [ticket/12549] Hide topic/forum list <dfn> tags in RTL languages.
Merge pull request #2466 from prototech/ticket/12550

[ticket/12550] Prevent last post column from jumping to second line in RTL.

* prototech/ticket/12550:
  [ticket/12550] Prevent last post column from jumping to second line in RTL.
Merge pull request #2467 from prototech/ticket/12551

[ticket/12551] Float breadcrumbs to the right in RTL languages.

* prototech/ticket/12551:
  [ticket/12551] Float breadcrumbs to the right in RTL languages.
Merge pull request #2480 from rxu/ticket/12572

[ticket/12572] Fix JS error when alert message title is undefined

* rxu/ticket/12572:
  [ticket/12572] Fix JS error when alert message title is undefined
Merge pull request #2468 from nickvergessen/ticket/12555

[Ticket/12555] Make use of canonical urls to avoid duplicate content

* nickvergessen/ticket/12555:
  [ticket/12555] Add canonical URL for viewtopic
  [ticket/12555] Add canonical URL for viewforum
  [ticket/12555] Add canonical URl for memberlist mode=viewprofile
  [ticket/12555] Allow to set canonical URLs to avoid duplicate content
[ticket/12583] Add event core.mcp_warn_post_before/after

Event for when warning a user for a post.

PHPBB3-12583
[ticket/12580] Remove :link pseudo from a tag

removed the :link pseudo from a tag as due to specificity it prevents
classes from altering any properties set to it.

PHPBB3-12580
[ticket/12531] Add some line breaks to really long lines

PHPBB3-12531
[ticket/12325] Automatic update should notify about outdated files

PHPBB3-12325
[ticket/12585] Use a 5 minutes interval instead of 10 minutes

PHPBB3-12585
Merge pull request #2490 from Nicofuma/ticket/12585

[ticket/12585] Don't check the cron on each page load

* Nicofuma/ticket/12585:
  [ticket/12585] Use a 5 minutes interval instead of 10 minutes
  [ticket/12585] Don't check the cron on each page load
Merge pull request #2444 from VSEphpbb/ticket/12531

[ticket/12531] Restore default topic link behavior to subsilver2

* VSEphpbb/ticket/12531:
  [ticket/12531] Add some line breaks to really long lines
  [ticket/12531] Restore default topic link functionality in subsilver2
[ticket/12325] Fix: it's not stuck in an inifinite loop anymore

PHPBB3-12325
[ticket/12270] Fixed topic counting bug and tests

Topics was not correctly counted (the counter didn't count topics
that were re-approved, for example, but only the ones that were
unapproved.
This should also fix the test that wasn't working correctly.

PHPBB3-12270
[ticket/12325] Don't use L_COLON

PHPBB3-12325
Merge pull request #2199 from Zoddo/ticket/12275

[ticket/12275] Fix a bug on the event "core.modify_username_string"

* Zoddo/ticket/12275:
  [ticket/12275] Change if (empty) to if (!isset)
  [ticket/12275] Fix a bug on the event "core.modify_username_string"