The idea is to provide a module that could be included by other UIs (by
dSS11 Web Setup in particular). The module should allow to restyle and
reorganize all tabs and elements without having to rewrite the
functionality.

The css has also been adapted; currently the same ds_gui.css is used
in the dSS11 Web Setup project; the dss_icons.css will hold icon
definitions that are specific to the dSS installer part.