WIP: minidom: Allow contextual NS to be passed when building element from reader

When reading from a (tcp|tls)stream, incoming stanzas generally look like so: <iq from='foo' type='result'>..</iq> and don't have any namespace declared because a default one is already declared on the stream (generally jabber:client or similar).

It is currently not possible with minidom to get this element returned with all the contextual namespaces we know, unless we pass the whole tree (that is, including <stream></stream>).

This method might not be the best but allows us to build upon and can be reworked later if necessary.

Signed-off-by: Maxime “pep” Buquet pep@bouah.net