Fix toggle all RISE buttons on slides

[YiqinZhang]

Fix toggle all RISE buttons and hard-wire both keyboards "m" and "," to hide/show buttons on the slideshow.

[fcollonval]

Hey @YiqinZhang what is the reason behind adding m - it seems that in the notebook extension only , is used.

[YiqinZhang]

Hi @fcollonval . Thank you fro your reply.
When I bound the shortcut to toggle the buttons, I found in rise.yaml and main.js, m was supposed to assign to toggleAllRiseButtons or at some point in time. So I added m to simulate the action. Nevertheless, I revised it to , and updated the pr.

[YiqinZhang]

Hi @fcollonval, I made some changes, and it's ready for review.

[fcollonval]

Thanks @YiqinZhang

As you stated earlier, m was assign at some point but now only , is binded. So thanks for changing the code to keep only ,.