added package-infos to lots of packages, updated the javadoc in these, and made lots of private/package private methods 'public' in packages that aren't actually public API. Tumi asked for this, and I can imagine this is useful for others who are hacking add-ons to lombok. The package-info files clarify that we aren't committing to long-term stability of anything except the stuff directly in the lombok package, lombok.experimental, and lombok.extern.