[Twisted-Python] Coil refactor more or less done

[Itamar Shtull-Trauring]

Andrew Bennetts wrote:

> A few small glitches I've found mucking about with it:
>   1) You can't delete a manhole service once you create one.

I'll check this out - I think it should be easy to fix, just write an extra 
method in the services collection.

>   2) If you create and configure an FTP server, connect to it, and then delete
>      it, you can still use the server from the existing connection.  I expect
>      that this might be hard to fix, and may even be desirable in most cases
>      anyway.

I'll see if I can figure this out.

>   3) There's no warning if you try to delete or replace the thing on port 9080
>      with something else, causing you to think you've broken the configurator
>      until you realise you've been an idiot :)

See my other email.