version 0.1.17 released

[mark.n...@gmail.com]

I have promoted the development version (0.1.17) to release version.
The sources are tagged with the label "release_0_1_17_alpha"

most prominent new features are
- info balloons that are shown when you hover over profile pictures
and links, and when that link is a twitpic link, the balloon will show
a preview of the picture
- the ability to configure different color schemes

And most importantly, the application has become much more responsive
because tweets are no longer rendered as a group of Text nodes, but as
a read only javax.swing.JEditPanel.

The next development version will be 0.1.18.