Rename set_default_page_list to apply_default_page_list and apply
during read_metadata
Add a filename attribute to the ImageMetadata class
Mark image_index as required
Always sort the page name list, a comic application will never need the
unsorted list of names
Assign the first result from get_cover_page_index_list to coverImage in
CoMet tags
Allow an Archiver to be passed to the ComicArchive constructor
