A big initial draft of the multiverse library and reading UIs, with a muted
look and minimalist chrome.  Includes Pure CSS and some vanilla CSS and JS.
Supporting HTTP `Cache-Control` and `ETag` for archive pages, borrowing on the
RAR and Zip internal CRCs.  It stands to reason that if a file can be found in
an archive and its CRC hasn't changed, it's the same file.
Support for PDF files where individual pages are JPEG images.  See the
docstring of the pdffile.py module for information about the source of the PDF
extraction code from Ned Batchelder's blog.