[ticket/12197] Fix several misleading FAQ entries

PHPBB3-12197
[ticket/12446] Unnecessary db connect inphpbb_bootstrap_enabled_exts

PHPBB3-12446
[ticket/12782] Use an interface for the phpbb event_dispatcher

PHPBB3-12782
[ticket/12782] Add doc block

PHPBB3-12782
[ticket/12099] Add request argument to path_helper service

PHPBB3-12099
[ticket/12099] Correctly fix the path when performing AJAX requests

If the current request is a AJAX we need to fix the paths.
We need to get the root path based on the Referer, so we can use
the generated URLs in the template of the Referer. If we do not
generate the relative path based on the Referer, but based on the
currently requested URL, the generated URLs will not point to the
intended locations:
	Referer				desired URL			desired relative root path
	memberlist.php		faq.php				./
	memberlist.php		app.php/foo/bar		./
	app.php/foo			memberlist.php		../
	app.php/foo			app.php/fox			../
	app.php/foo/bar		memberlist.php		../../
	../page.php			memberlist.php		./phpBB/
	../sub/page.php		memberlist.php		./../phpBB/

PHPBB3-12099
[ticket/12099] Remove config again

PHPBB3-12099
[ticket/12099] Add unit tests for get_web_root_path_from_ajax_referer()

PHPBB3-12099
[ticket/12787] Use a parameter (_referer) instead of the Referer header

PHPBB3-12787
[ticket/12787] Fix the absolute board url

PHPBB3-12787
[ticket/12788] Update symfony components

PHPBB3-12788
[ticket/12788] Force 2.3.* on symfony dependencies

PHPBB3-12788
[ticket/12802] Properly handle connection failures in SQLite3

PHPBB3-12802
[ticket/12013] Use new dropdown for quickmod tools and jumpbox.

PHPBB3-12013
[ticket/12013] Use path helper.

PHPBB3-12013
[ticket/12013] Use DEFINE instead of Twig's set.

PHPBB3-12013
[ticket/12013] Use the correct variable for the forum id.

PHPBB3-12013
[ticket/12013] Add missing class to place the buttons on the rightside.

PHPBB3-12013
[ticket/12013] Update to use the new .button class.

PHPBB3-12013
[ticket/12013] Prevent the dropdown scrollbar from overlapping the content.

PHPBB3-12013