- Factored out duplicate code from filemanager.lua and filemanagerhistory.lua
to new filemanagerbookinfo.lua (and other common code to filemanagerutil.lua).
- Uses sidecar files' new doc_props and doc_pages settings, or fallback to
old 'stats' settings, or to opening document.
- Shows filename, filetype and directory.
- Shows description (Hold to see whole truncated text), keywords, and
cover image (tap to extract image from document and display it if available).
- Book information now available from reader menu, to display info about
the currently opened book.
- Convert possibly HTML description to plain text via added
util.htmlToPlainTextIfHtml() (for simple HTML conversion).
util.isSplitable() accepts now also the previous char to help
decide if a space can be used to split a line.
TextBoxWidget:_splitCharWidthList() : simplified logic
util: made isSplitable() accept an optional next_char
for wiser decision
textboxwidget: speed up rendering, enhanced text wrapping,
allow selection of multiple words with Hold.
scrolltextwidget: allow scrolling with Tap.
Details in #2393
