configuration and runtime of kscreensaver/xscreensaver

[Marc Espie]

I'm not quite sure who is in charge of this sub-project, but
kxsconfig is doing things all wrong, especially from a packager
point of view.

Detecting which screensavers are installed, and only installing the
corresponding desktop files is a bad idea. This is definitely filtering
that should happen at runtime, not build time.

On OpenBSD, we've got at least two distinct screensaver packages,
depending on whether we want to use gle or not...

kscreensaver should be able to build the same way independently of
which packages are installed, and then to use whatever is around.

I would expect distros like debian to be even worse in that respect,
with about one package per screensaver module ;-)