* Reader menu: adds "Open previous document"
Allows for quick switching between 2 documents, and keep
symmetry with FileManager menu "Open last document".
* Use "Last:" and "Previous:" when Show filename
This adds a button to the Tap Plus menu, that allows
extracting metadata and cover images for books in
current directory. Info about the process and questions are
initially shown and asked, and the process can be aborted at
any moment.
Speedup initialization (needs to be done only once, and avoid
saving current mode to sqlite each time) and reader-to-filebrowser
switch, by doing a single rendering (instead of 2 or 3 previously).
ListMenu: cache sidecar file parsing results (page/percent
completed) for the browsing session duration.
Fix "No choice available" when on last page and changing
to a display mode with less pages.
Made the onHold buttons table similar to the one of File browser.
Added "Purge .sdr" and "Delete" to these buttons.
Moved the purgeSettings and removeFileFromHistoryIfWanted
logic into filemanagerutil functions.
Stay on the same page when manipulating history (previously, we were
always put back on first page).
Really keep deleted files in history (unless setting says otherwise).
Show deleted files in grey or dimmed in classic History and all
CoverBrowser display modes.
* CoverBrowser plugin: alt views for File Browser and History
* Added Prune cache and Compact cache menu actions
* Support for book descriptions, and settings stored in db
