use Composer autoloader not OC for non-Composer 3rdparty (#9643)

Composer's autoloader is rather better than the OwnCloud autoloader's
handling of non-OC classes. Plus we can rely on upstream Composer to
maintain it and not worry about it ourselves.

With this change, we drop the bits of OwnCloud's autoloader that
handled non-OC classes, and register the classes that were being
handled by that code with Composer's autoloader instead. As these
dependencies are converted to actually being managed by Composer,
the explicit registrations can be dropped as they won't be needed
any more.

Since OwnCloud's autoloader isn't going to handle non-OC classes any
more, we no longer need to test to make sure it does it right.

drop unneeded registerPrefix() and registerClass() from autoloader

Now we're not handling anything but OC's own classes, these are
unnecessary.

error out if composer autoloader is not found (thanks bantu)

We're never going to be able to work without the autoloader, if it's not
there we should just throw our hands up and surrender.
Merge pull request #11805 from owncloud/AdamWill-issue9643

use Composer autoloader not OC for non-Composer 3rdparty (#9643)
Use composer autoloader to load Patchwork
Merge pull request #11738 from owncloud/update-patchwork-utf8

Use composer autoloader to load Patchwork
[tx-robot] updated from transifex
l10n.pl now generates js files as well
Added OC.L10N namespace with translation functions

Added addTranslations and fixed de.js file

Fixed de.js to use OC.L10N.register() and use to correct expected
format.

Added JS unit tests for OC.L10N class

Include translations JS script for all apps
in case a translation javascript is not found we no longer bail out

remove translation.php
Include core translations

Moved search result type translations to search.js

Load JS translations earlier

Translations need to be loaded earlier to make sure that some JS files
like search.js get access to translations at this time.

This requires the template initialization to be moved to after session
initialization, because only after the session we have access to the
current language.
adding console command to generate javascript translation files based on existing php translation files
read server side translations from json files
update all translation files to js and json
Fix language file detection
Add missing de.js files