[gnome-db] Code cleanups

[Vivien Malerba <vmalerba gmail com>]

Hi!

I'm doing some code cleanups and I want to remove the following parts
in libgda and libgnomedb which don't seem to be used anywhere. Please
tell me if you have any objections.
-> libgnomedb/providers
-> libgnomedb/vfs
-> libgda/libgda/gda-xql* as there is no doc on how to use it and I'm
not sure it's the correct API to implement XML queries.

What do you think?

Vivien