Fix Ajax type casting for files_external

Better caching for enabled apps

Fix some PHPDocs

Update license headers

Use "off" and "off" instead of true booleans

DAV authentication: use Owncloud's internal user instead of HTTP auth one

Apparently a boolean in php.ini is according to the documentation "on" or "off"…

Fixes itself.

Add helper to check for `ini` values in `OC_Util::checkServer`

Check for PHP configuration before executing unit tests

This allows to check for specific values in the PHP.ini that ownCloud requires for full compatibility.

`mbstring.func_overload`: https://github.com/owncloud/core/issues/14372
`output_buffering`: http://doc.owncloud.org/server/8.0/admin_manual/configuration/big_file_upload_configuration.html#configuring-php

Fixes https://github.com/owncloud/core/issues/14372 and https://github.com/owncloud/core/issues/14412

Close cursor for appframework and manipulation queries if applicable

Use insertIfNotExists() and reload mimetypes after inserting one

Correctly create the expected key for plurals with quotes

Check if the offset exists before accessing

Add `Satisfy All`

Parse backslash as directory separator in breadcrumb

Remove some old l10n files they arent loaded anymore

Manually type-cast all AJAX files

Streamline auth and CSRF check in scan.php

Encode requesttoken

Encode Requesttoken for avatars

Fix #14310

Port of #14041 to master

on ownCloud upgrade: upgrade all apps in order, load important ones

Fix "other" app update stack

If no link text has been set for the navigation show the link nonetheless

Disallow path traversals in file view