[ticket/12540] Fix broken placeholders in language files

PHPBB3-12540
[ticket/12435] purge_notifications() fails for unused notifications

https://tracker.phpbb.com/browse/PHPBB3-12435

PHPBB3-12435
[ticket/12544] Update Plupload to 2.1.2.

PHPBB3-12544
[ticket/12435] Update the comment

PHPBB3-12435
[ticket/12533] Make <a> use all the notification item size

Changed padding CSS to the notifications' `<li>` and it's
`<a>` (immediate child) so that the `<a>` block uses all
 it's container width and height.

To compensate that, I added the padding that was in the
`<li>` to the `<a>`

PHPBB3-12533
[ticket/12533] Make <a> use all the "see all" "button"

Changed the CSS so that the `<a>` of the notifications
list for the "see all" uses all the container.

PHPBB3-12533
Merge pull request #2457 from prototech/ticket/12544

[ticket/12544] Update Plupload to 2.1.2.

* prototech/ticket/12544:
  [ticket/12544] Update Plupload to 2.1.2.
Merge pull request #2456 from Nicofuma/ticket/12435

[ticket/12435] purge_notifications() fails for unused notifications

* Nicofuma/ticket/12435:
  [ticket/12435] Update the comment
  [ticket/12435] purge_notifications() fails for unused notifications
[ticket/12547] Rename jquery.js to jquery.min.js in assets directory

phpBB uses the minified version of jQuery hence the rename.

PHPBB3-12547
Merge pull request #2454 from nickvergessen/ticket/12540

[ticket/12540] Fix broken placeholders in language files

* nickvergessen/ticket/12540:
  [ticket/12540] Fix broken placeholders in language files
Merge branch 'develop-olympus' into develop-ascraeus

* develop-olympus:
  [ticket/12540] Fix broken placeholders in language files

Conflicts:
	phpBB/language/en/common.php
	phpBB/language/en/posting.php
	phpBB/language/en/ucp.php
[ticket/12433] Use a different message when nesting of quotes is not allowed

PHPBB3-12433
[ticket/11163] Add ext/index.htm

PHPBB3-11163
Merge pull request #2464 from nickvergessen/ticket/11163

[ticket/11163] Add ext/index.htm

* nickvergessen/ticket/11163:
  [ticket/11163] Add ext/index.htm
Merge pull request #2463 from nickvergessen/ticket/12433

[ticket/12433] Use a different message when nesting of quotes is not allowed

* nickvergessen/ticket/12433:
  [ticket/12433] Use a different message when nesting of quotes is not allowed
[ticket/12551] Float breadcrumbs to the right in RTL languages.

PHPBB3-12551
[ticket/12549] Hide topic/forum list <dfn> tags in RTL languages.

PHPBB3-12549
[ticket/12550] Prevent last post column from jumping to second line in RTL.

PHPBB3-12550
[ticket/12555] Allow to set canonical URLs to avoid duplicate content

PHPBB3-12555
[ticket/12555] Add canonical URl for memberlist mode=viewprofile

Avoids duplicate content of:
* memberlist.php?mode=viewprofile&u=user_id
* memberlist.php?mode=viewprofile&un=username

PHPBB3-12555