Before this change RequestContext::get_query() returned a reordered
query string (alphabetically sorted by the parameter names).
This fix facilitiates testing of responses where the request URL appears
in the response.
If the server is initialized with a library.xml file, then the id
specified in the XML file is used (rather than the UUID recorded in the
ZIM file).
Note that in test/data/library.xml the book ids are fake and
different from the real ZIM IDs; that file was created for testing
of the /catalog endpoint which doesn't access ZIM content, so the
the same ZIM file zimfile.zim was added to library.xml three times as
three different books (with unique human-friendly ids). This explains
the diff in test/library_server.cpp.
Veloman Yunkan
Matthieu Gautier