Creating a new pre-authentication plugin

[Luke Howard]

> Sure, but note that even if the mechglue does not do that, doesn't mean it shouldn't do it :). Looking at the specs, GSS-API has the ability to return some kind of INVALID_CONTEXT error code.

It actually used to do something like this, as Greg pointed out. I think it got ripped out as it was done inconsistently and/or made the code somewhat hairier.

-- Luke