FR: Save read page duration limits per book

[jonnyl2]

Does your feature request involve difficulty completing a task? Please describe.

Read page duration limits are currently stored globally. This is not a problem for reflowable docs as they are usually set up to a more or less similar amount of words per page. However, word counts per page on fixed-layout books can vary widely, where scanned booklets can have as little as 100 words per page and A4-size pages with small font up to 1000 words (those documents are then read in reflow mode or zoomed in).

On books with larger word counts per page I'd like to be able to set the upper limit to a higher number without it affecting other books (or having to adjust it each time when switching between books).

Describe the solution you'd like

Store the read page duration limits per book (or per fixed-layout book).