We have to reuse the query the user give us to generate the
pagination links.
At search result rendering step we don't have access to the query object.
The best place to know which arguments are used to select books
(and so which arguments to keep in the pagination links) is when we
parse the query to select books.
Fix tests (pagination links) with book selector other than "books.id="
(pattern=jazz&books.query.lang=eng)
Introduces a new member mp_search that houses the zim::Search object,
adds a new constructor for this purpose. This commit also add an
overload for getHtml that takes start and end integers as arguments
since they are not part of the search object we include.
