[Twisted-Python] cReactor fixes

[Brian Warner]

Itamar Shtull-Trauring <twisted at itamarst.org> writes:
> 
> As I said, if cReactor has addReader/addWriter interface
> twisted.internet.interfaces.IReactorFDSet, we get ssl, udp, multicast,
> serial and process support almost for free using the python code for
> these, until a C version is written.

Good point. And, the performance difference between having the fileno
originate from python code vs. having it originate from C code won't be an
issue until you're creating lots of sockets, so as long as the functionality
is present, moving it to C can wait until someone has a need for it.

I'll look into gluing IReactorFDSet into cReactor.

 -Brian