Callback property functions with list of arguments.
Add prodigy-callback function.
SSH-tunnel example.
Flyspell to the rescue... (fixed typos).
Comment on the `cl.el` usage.

It's nice for people, who don't yet know about elisp <-> clisp, not to
be surprised.
Merge branch 'property-function-arguments'
Adding v0.6 release notes.
Merge branch 'tomterl-ssh-tunnel-example'
Release v0.6.0.