auth-source

This is the auth-source.el package.  It lets users tell Gnus how to
authenticate in a single place.  Simplicity is the goal.  Instead
of providing 5000 options, we'll stick to simple, easy to
understand options.

See the auth.info Info documentation for details.

TODO:

- never decode the backend file unless it's necessary
- a more generic way to match backends and search backend contents
- absorb netrc.el and simplify it
- protect passwords better
- allow creating and changing netrc lines (not files) e.g. change a password