[gnome-db]XML Query

[Malerba_Vivien stna dgac fr]

Hi all!

I've finally comitted the xml query implementation done by Gerhard, with few
modifications:
* a Makefile.am and the necessary modifications in the gda-common/Makefile.am
* added a check for GOB in the configure.in file
* modified a bit the sources to make the lib build with libxml 1.8.x (x>10)
and 2.2.x
* moved the test program in the testing directory

What remains to be done is:
* library version numbers (instead of libxmlquery.0.0.0)
* fix a bug in xml-query-item.gob line 126 where the DTD should be looked for in
the future DTD install directory (instead of the current directory now).

I have tested what I could on my machine, and if you find some problems, please
tell me!

Enjoy,

Vivien