[ticket/11997] Correctly redirect to front controllers

We currently do a lot of checks in order to prevent users from getting to
a 404 page. However, this logic relies on checking if a file or folder exists.
Due to the front controllers and the URL rewriting in 3.1, it is no longer
possible to rely on existing files for redirecting. This patch will take
care of properly redirecting users to front controller files. An incorrect
link will cause users to get a 404 error though.

PHPBB3-11997
[ticket/11997] Remove obsolete if statement in phpbb_own_realpath()

PHPBB3-11997
[ticket/11997] Rename root_dirs_size to superordinate_dirs_count

This variable name better fits what is done with it. A comment explaining
why 2 has to be subtracted from the size of root_dirs has also been added

PHPBB3-11997
[ticket/11997] Use $phpbb_filesystem->clean_path() for proper redirect paths

PHPBB3-11997
[ticket/11997] Fix redirects from inside controllers

The redirect url currently uses the web root path. However as we prepend the
full board url later, we need to remove the relative web root path and prepend
the normal root path again. Otherwise redirects from inside routes will not
work as intended.

PHPBB3-11997
[ticket/11997] Fix missing global

PHPBB3-11997
[ticket/11997] Add functional test for redirects in controller

PHPBB3-11997
Merge pull request #4 from nickvergessen/ticket/marc/11997

Ticket/marc/11997
[ticket/11997] Remove obsolete failover_flag in function redirect()

This flag is no longer needed as the failover is no longer needed.

PHPBB3-11997
[ticket/12039] Add config:* to the command line interface tool

PHPBB3-12039
[ticket/12039] Use an abstract class and some more minor adjustments

PHPBB3-12039
[ticket/12039] Fix option descriptions

PHPBB3-12039
[ticket/12039] Remove debug code

PHPBB3-12039
[ticket/11997] Undo changes to phpbb_own_realpath()

PHPBB3-11997
[ticket/11997] Add method for controller redirect URLs to path helper

This method will allow us to get proper redirect URLs for controllers.

PHPBB3-11997
[ticket/11997] Use get_controller_redirect_url() in redirect() function

This method of path_helper will now be used instead of the previous hack
of the phpbb_own_realpath() function.

PHPBB3-11997
[ticket/11997] Fix tests for path_helper's get_controller_redirect_url()

PHPBB3-11997
Merge branch 'develop' of https://github.com/phpbb/phpbb into ticket/11997

Conflicts:
	tests/functional/fixtures/ext/foo/bar/config/services.yml
[ticket/12030] Include config directory completly in update packages

When one of the config files was updated, we need to include all config files
because they are referenced relative from the files themselves.

PHPBB3-12030
[ticket/12030] Include adm/images/ when the css file was updated

The images are referenced relative from the admin.css file.
So when it was updated and the images where not, the updater will be without
images, unless we ensure that they are included in the update-package.

PHPBB3-12021
PHPBB3-12030