Enable better javadoc integration

[evanlenz]

The idea here is to display the javadoc results in the content pane (rather than only provide external links). The TOC pane could then list all the classes grouped by package. Users could still of course click over to the javadoc if that's what they want.

[evanlenz]

bonus points: include a "By class" and "By package" switcher

[dsokolsky]

And even more bonus points for a way to pop-out the whole javadoc.