- add a separate toolbar for the deck browser
- add a message when there are no decks
- change the progress handler not to lock the UI immediately, which causes
flicker
- ensure the webview is focused after stdHtml()
- moved progress handling into separate progress.py
- moved deck browser code into separate deckbrowser.py
- started reworking the state code; views will be rolled into this in the
future
- the main window has been stripped of the study options, inline editor,
congrats screen and so on, and now consists of a single main widget which
has a webview placed inside it. The stripped features will be implemented
either in separate windows, or as part of the web view
