[ticket/11480] PM : "Unknown folder" returned when inbox folder is full

https://tracker.phpbb.com/browse/PHPBB3-11480

PHPBB3-11480
[ticket/12325] Automatic update should notify about outdated files

PHPBB3-12325
[ticket/12325] Fix: it's not stuck in an inifinite loop anymore

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

PHPBB3-12325
[ticket/12325] Fix: add a missing colon

PHPBB3-12325
[ticket/12492] Add support of special chars

Add support of special chars during db test in the installation

PHPBB3-12492
[ticket/12325] Update coding style in template

PHPBB3-12325
[ticket/11480] Add functionnal test

PHPBB3-11480
[ticket/11480] Fix typos

PHPBB3-11480
[ticket/12099] Fix several issues in path_helper test

PHPBB3-12099
[ticket/12099] Clean some paths before using them

PHPBB3-12099
[ticket/12099] Correctly fix go back to root before prepending the root path

This allows moving app.php outside of phpBB and still work as expected

PHPBB3-12099
[ticket/12099] Clean paths in tests

PHPBB3-12099
[ticket/12099] Break clean_path tests with a simple test

PHPBB3-12099
[ticket/12099] Fix clean_path() ".." stripping when previous directory was "."

PHPBB3-12099
[ticket/12325] Fix the language var name

PHPBB3-12325
[ticket/12099] Deduplicate path generation

PHPBB3-12099
[ticket/12099] Prepend ./ to path to fix assets

PHPBB3-12099
[ticket/12099] Fix correction in path_helper test

PHPBB3-12099
[ticket/9801] Allow display of page outside board directory on viewonline

Until now, the preg_match didn't take into account that a page might be
outside the board directory. After this change, the regular expression will
allow preceding dots and slashes. Paths like ../../test.php will be allowed.
The page will be unknown in viewonline.php and it will revert to index.php as
current page. However, the core.viewonline_overwrite_location event will
receive proper info of the page the user is on right now allowing a listener
to change the info that is being displayed.

PHPBB3-9801