XSL extension: fix tests in Repo.Authoritative mode.

Just inlined an included file. Is there a way to tell the testsuite
to add the file to the repo instead?

Signed-off-by: Arthur Loiret <arthur.loiret@ens-lyon.fr>
XSL extension: improve handling of node args.

Signed-off-by: Arthur Loiret <arthur.loiret@ens-lyon.fr>
XSL extension: cleanup code.

Signed-off-by: Arthur Loiret <arthur.loiret@ens-lyon.fr>