Hooks for toggling

[matthewturk]

Hi! I love this plugin. I was wondering if it might be possible to put hooks in for toggling. This might be something that could be made generic, but the one hook that I think I would really benefit from would be to auto-toggle to make sure I'm not in vim mode when I add a card to a Canvas.

It might be sufficient to be able to do this just when file-open is triggered and the new file is a canvas -- have it drop back from vim mode then. This could be stuck behind a toggle setting.

This may be out of scope for this plugin, but it also seems like the best place for it. Would you be open to a PR implementing it?