Make Xml possible in the parse tree + misc improvements

[dinosaure]

See #21 and #22.

[Chris00]

See https://github.com/Cumulus/Syndic/pull/22 that I rebased on master. It does not have https://github.com/Cumulus/Syndic/commit/28ce2e0285accff08a953e098e223e21c29ddac5 though. I am a bit lost on what you want to do.

[dinosaure]

I use exception Ignore_namespace for this line. The exception is local to a function generate_catcher and we should not manage without.

Another problem is namespace. Indeed, eeb85ef adds a namespace to all the generate_catcher (partial application does not to work). I think the history of namespaces (namespace worth "") is specific RSS 2.0.

I think change generate_catcher for that the list of tags optionally contain namespace more specifically (RSS 1.0 contains two namespaces for example, RSS 1.0 and RDF).

[dinosaure]

Ready to merge or another point (speciallement on namespaces) ?

[Chris00]

Your solution is working but maybe the logic couls be clearer? What about soluting along the lines

    let in_namespace ((prefix, _), _) = List.mem prefix namespaces in

(on purpose not restricted to a specific type) and then

 let rec catch_datas acc = function
      | Node (tag, datas) :: r ->
         if in_namespace tag then
           match get_tag_name tag data_producer with
           | Some f -> catch_datas ((f acc (tag, datas)) :: acc) r
           | None -> catch_datas acc r
         else
           catch_datas acc r

[dinosaure]

Indeed, working on master now, thanks !