use a pop-up menu instead, which saves a lot of screen real estate and
should be more intuitive for new users
also:
- add options to manage note types and clear unused tags in the relevant
submenus
- shuffle a few shortcut keys
- remove the old favourites code - saving and removing now done via the
menu
- individual card templates now searchable
- a few issues to work out still, and editor changes not done yet
- for communication between webengine and python code, we set window
.location to 'http://anki/<something>' - the leading http is
necessary for qt to call the link handler, which was introduced
in qt5.5
- the designer files now use a promoted qobject to create instances
of AnkiWebView
- we use the css zoom property to alter webengine font size based on
system dpi
- prefs and addons folder stored in new location (at least for now)
