Configurable CLI Subrequest environment variables
When debugging with xdebug, a major difficulty is that in development and
functional tests, there are always two requests being executed: The main request
and a CLI request inside.
Now, most IDEs do not support the (optional) feature of multi-threaded PHP debugging,
effectively stopping the sub-request and also the main request in this case.
With this feature it's possible to change the XDEBUG remote port from 9000 to 9001, so that the subrequest can be debugged by listening on port 9001.