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

Fixes itself.

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

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

Fix "other" app update stack

Fixes https://github.com/owncloud/core/issues/14356

This prevents a misusage of \OC\Files\View by calling it with user-supplied input. In such cases an exception is now thrown.

Somehow they got messed up. Because PHP does automatic type juggling this has worked before as well however it's not guaranteed that this might work in the future as well.

Due to a security hardening in 8.1 a missing value of empty trusted domains in the config would provoke an error as this was misused by a lot of users.

This caused a problem where the initial installation happened from another domain than 127.0.0.1 as in this case the domain was considered untrusted as no value was defined. However, this special case should not get intercepted.

To test:
- [ ] Installing ownCloud on 127.0.0.1 works
- [ ] Installing ownCloud on another domain / IP works
- [ ] When setting up ownCloud from 127.0.0.1 and accessing it from the domain above the trusted domain error should be shown if not specified in the config

Fixes https://github.com/owncloud/core/issues/14320

APCu before 4.0.6 is unbelievable buggy and tend to segfault the PHP process (i.e. the whole webserver)

This potentially fixes https://github.com/owncloud/core/issues/14175

Requires a backport to stable8

It still works otherwise, but without this, the performance optimization
of #13416 is defeated in these situations.

Fixes: #14048, #14104, calendar#712

This changeset removes the static class `OC_Request` and moves the functions either into `IRequest` which is accessible via `\OC::$server::->getRequest()` or into a separated `TrustedDomainHelper` class for some helper methods which should not be publicly exposed.

This changes only internal methods and nothing on the public API. Some public functions in `util.php` have been deprecated though in favour of the new non-static functions.

Unfortunately some part of this code uses things like `__DIR__` and thus is not completely unit-testable. Where tests where possible they ahve been added though.

Fixes https://github.com/owncloud/core/issues/13976 which was requested in https://github.com/owncloud/core/pull/13973#issuecomment-73492969

This change allows AppFramework applications to specify a custom CSP header for example when the default policy is too strict. Furthermore this allows us to partially migrate away from CSS and allowed eval() in our JavaScript components.

Legacy ownCloud components will still use the previous policy. Application developers can use this as following in their controllers:
```php
$response = new TemplateResponse('activity', 'list', []);
$cspHelper = new ContentSecurityPolicyHelper();
$cspHelper->addAllowedScriptDomain('www.owncloud.org');
$response->addHeader('Content-Security-Policy', $cspHelper->getPolicy());
return $response;
```

Fixes https://github.com/owncloud/core/issues/11857 which is a pre-requisite for https://github.com/owncloud/core/issues/13458 and https://github.com/owncloud/core/issues/11925