The widget audit

The widget audit is making good progress.

I am about to embark on a complete rewrite of tab/tabpane to make full use
of cardpane, selectable and focusable.  Rod has done some sterling work on
tree which is looking good.  Once those two are complete, we will rerelease
the XWT demo with the new widget set.

I'm also busy refactoring table.  I'm pushing the layout of table into
grid/row/column which effectively mirror html's table/tr/td, and table will
be an application of this.

Also, Rod and I have made a start on moving stuff into the new namespace,
over on mixdown.ca.  We are also being consistent and renaming the themes
dir (org.xwt.themes) to org.xwt.theme (no s).  I'll hopefully make an
announcement at the end of this week with a link to the demo.

The new widgets are not properly documented etc and this is a
post-working-widgets task.

Thanks for the patience.  We hope you'll all be pleased with the new widget
set.

- Charlie