Make sure all request parameters are used by the script, otherwise trigger the error 404 page (see #4277)
Added a switch to determine whether an `Input::setGet()` parameter will be checked (see #4277)
Do not initialize `$arrUnusedGet` with the `$_GET` array
Merge branch 'feature/check-request-string' into develop

Conflicts:
	system/modules/core/library/Contao/Input.php