blindfold toggle keybinding + initial wait

[vdegenne]

In this pull request, I added 2 things :

• An initial wait in the init function. For some reasons chess.com is updating the chessboard 2 times on page load, it makes the blindfold state useless. I saw you are using a localstorage to save the toggle value, waiting makes sure the blindfold is loaded back on page refresh.

• A keyboard shortcut (ctrl+b) for toggling on/off the blindfold as well. I've updated the UI to make sure users know about this new shortcut.

What do you think?

[everyonesdesign]

Hello! And sorry for the loooong response time.

An initial wait in the init function. For some reasons chess.com is updating the chessboard 2 times on page load, it makes the blindfold state useless. I saw you are using a localstorage to save the toggle value, waiting makes sure the blindfold is loaded back on page refresh.

Could you elaborate on this? Is something not working or is it an optimisation?
For me the blindfold mode is initialised every time correctly and without delays (I cannot see the position of pieces, tested in Chrome).

A keyboard shortcut (ctrl+b) for toggling on/off the blindfold as well. I've updated the UI to make sure users know about this new shortcut.

Initially I was concerned about keys collision with other shortcuts, but in this case I think that's OK.
Do you think it's better to reassign the shortcut to Cmd+B for macOS users? I think Cmd is a more frequently used modifier key there.

It also seems that some tests are failing in this branch, I'm not sure if we need to rebase it or something got broken. I might check later.