* Flattening OPDS Structure
# Changed
- Flattened OPDS structure to reduce user taps.
* Fixing format
* Fixing book series titles
* Optimized file size to use pre-calculated data to avoid an I/O touch.
* Fixes#1898 by aligning all content headers to the correct MIME types
* Remove dead code
* Fixed a bug with continue point where it fails on chapters or volumes tagged with a range
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Co-authored-by: Robbie Davis <robbie@therobbiedavis.com>