[Twisted-Python] usage.Options

[Brian Warner]

> Adding a user/pass to the existing authorizer (which it did) may not be
> such a bad idea as you seem to suggest, since you only give that new
> identity a key for the "twisted.manhole" service and not the other(s).
> (...but authorizers are now per-Service, not per-ServiceCollection, so you
> can still have your separate one if you wish, even if you put them on one
> port under the same broker factory.)

Good point. I was worried about interaction with a user's custom Authorizer
subclass (which might do some funky db or ldap thing). But adding an auth for
just the manhole service would avoid that cleanly.

> it's a somewhat abusive hack.  Modules in the 'tap' package are for use
> with mktap, and "usage" is a command-line processing utility, not a more
> comprehensive configuration tool such as coil might be.

I agree completely. Manhole is such a great debugging aid (and a great
learning tool, as the beginning developer is trying to match up what they see
in the source code with the internal behavior of a live app) that I wanted a
simple non-confusing way to add one. So I think that addManhole might be a
reasonable addition.

I'll see if I can make a version that checks for an existing factory and adds
to it if necessary. That probably means addManhole() has to be the last one
added (because other services won't do the same thing), but that's easy
enough to add to the docs.

thanks,
 -Brian