In long standing cygwin installations, many no longer needed 
automatically installed packages (e.g. libicuNN) accumulate. This patch 
adds a new view which is possibly helpful to cleanup packages manually.

Some possible later enhancements:
- automatically refresh this view (a few seconds) after the user changed 
a package status as this may add or remove entries.
- add a keyboard shortcut (^U) to the list view for "Uninstall this 
package and then select next package"

-- 
Regards,
Christian