Add Symfony routing component as dependency.
Use The Symfony router to handle backend Url's.

Note: for now, we just set the application name from this "controller".
We allready have our module, action and language variables here. These
should be passed to the Action class.
Handle Ajax and cronjobs by the symfony router.
Add routes for all basic applications.
Add phpDoc
Remove useless defined checks.

The router is the only place in Fork where we define applications.
There's no need for unnecessary defensive programming.
Refactor out duplicate code.
Add credit
Remove unused use statement.
Load routes from a routing.yml file.
Remove unnecessary use statements.
Remove the legacy BackendDirect application type.
Avoid url's with trailing slashes.

They still give problems at this moment with the Symfony routing
component.
Add the Symfony FrameworkBundle as a dependency.

This way, we'll be able to use the Symfony routing from the
Frameworkbundle.
Make the Kernel similar to the Symfony kernel.

Only the request handling and the defineForkConstants are still custom
functions.
Make sure the kernel still works with our current code.
Add the Symfony console.

This way, it'll be easier to check if all needed services are registered
correctly.
Remove unnecessary dependencies in composer.json
Let the Symfony framework bundle handle routes.
Remove unused legacy code.