a new class called BookVersions.Code.HiddenPageClass with a boolean property called hidden,
an option in the Versions menu to mark/un-mark the page hidden,
in the publication preview the hidden pages would be marked as such and
at publication time, if the source page has the BV hidden flag on, make the target document hidden (the standard XWiki attribute)
in the master space, a message saying that this page will be hidden at publication displayed by the navigation menu (like the no content message for instance)
as a side note, pages which have been hidden directly with the standard feature should also be published as hidden (easily reachable by user for unversioned, less easy for the versioned top page)
New Feature
Major