Various server related things that I intend to get to soon-ish, in no
particular order.


New features for the in-browser viewer
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- Footnote popups

- Bookmarks and more generally, annotations such as highlighting text and
  adding comments

- When reaching the end of the book, show a popup that allows the user
  to rate the book and optionally delete it from the local storage.


New features for the server generally
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- Create a UI for making changes to the library such as editing metadta,
  adding/deleting books, converting, sending by email, etc.

- Add a way to search the set of locally available books stored in offline
  storage.


Bug fixes
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