QIODevice needs closing (and other end-of-request signals)

[halfgaar]

The project may be stale, but I'm happily using it, so here goes:

QFCgiStream is a derived QIODevice. As the docs for ~QIODevice say:

This destructor does not call close(), but the subclass destructor might. If you are in doubt, call close() before destroying the QIODevice.

If I implement that, it properly fires the aboutToClose() signal, which I need for resource cleanup. The QFCgiRequest may actually also need some signals for that, (like connectionClosed() or requestEnded() (the difference may be keep-alive connections, of which I don't know (yet) how they work in FCGI).