Add a reference to the plugin object in the Tool class and also improve
documentation a little
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E-book viewer: Make the Table of Contents panel a dockable window so it can be moved around and even made into a separate floating window

Also refactor the viewer's ui code to not use Qt Designer.
E-book viewer: Resize the metadata overlay view when the viewer window is resized
E-book viewer: Make the list of bookmarks a dockable window that can be kept open while reading the book
Viewer: Fix positioning of full screen labels when dock windows are present
Refactoring
Add a context menu to the bookmarks view to sort bookmarks by name or book position
Update Maximum PC
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When adding a new bookmark select it in the bookmarks panel
Add delete bookmark to context menmu and keyboard shortcut
Edit Book: Fix choosing default dictionary based on language tag in the OPF ignoring the country code
Refactor
EPUB metadata: When updating the language in an EPUB file, preserve the country code, if the new language is the same as the original language in the EPUB file.
ebook-edit: Allow specifying multiple internal files to open and get rid of the unneeded --edit-file option.
pep8