This will do for now to meet popular demand

"Advanced Open File" menu opens a "media" chooser, an "Open Media" named
dialog. Keeping "Open File" is wrong then.
Compared to this menu, Open "File", "Network", "Capture" and "Disc" are
just 'shortcuts': They needed to be grouped then.

This temporarily removes CAM support (which was reportedly broken a few
days ago). Scan is left for the time being.

Use cqam:// as BDA already does.

(there was no guarantee that each graphic item could be safely casted to
epgitem)