Add more key bindings + ability to assign own key bindings

[ans87gh]

Is your feature request related to a problem? Please describe.
Works well. Some key bindings interfere with normal webpage elements ie f for fullscreen while playing a video on YouTube. So you rarer stuck prioritizing vim functionality or page usability.

Describe the solution you'd like
Option to assign own keys to actions. Also, please port other key bindings from Vimium. There is a large selection of actions that are just great. The most helpful would be ? (⇧ /) to see entire list of bindings. Another I'd be interest in are ⇧ x to undo closing tab, but there are plenty more.

Describe alternatives you've considered
Can't think of any.

Additional context
None

[nbelzer]

Thanks for the report @ans87gh. I'm happy to tell you that the configuration of keybindings is now present in the master branch (by #175). I'll leave your issue with the request for the two keybindings.