Annotea presentation objects

I finally did some "real" work on Annotea Presentation objects.

The goal is to be able to define presenting order and other such 
properties for bookmarks and topics but separately from them. This 
helps, for instance when users subscribe different bookmark files.

I also made a new version of Annotea Ubimarks that understands this 
format. I will send link to it as soon as I check couple of other things 
and package it.

Right now I'm looking for feedback and ideas. The draft schema is 
currently in http://www.annotea.org/schemas/2006/04/presentation.rdf
I use rdf:Seq instead of collection because Mozilla does not yet know 
how to do collection.

A simple test file is located in 
http://www.annotea.org/mozilla/testdata/test3.rdf

Marja