Adds simple keyboard accessibility to toggle popup on enter, close with escape key

[betweenbrain]

Hello,

We are working on implementing a more accessible version of this component and hope that we can contribute these changes back to your project.

Cheers!

[mst101]

Hi @betweenbrain - I've also been working on this. In addition to the changes you've suggested, I'm planning to also allow for navigation via the arrow keys.

I've pretty much cracked that, but am struggling with issues related to the focus, in particular how to close the calendar when you click elsewhere on the page also how to prevent issues like #77.

I'll let you know once I've uploaded a clean version of my work-in-progress later today and would really appreciate it if you (and/or others) could have a look and offer your ideas. Thanks

[mst101]

Please see #81.

[betweenbrain]

I'm closing this PR as I am going to re-evaluate the approach for better backwards compatibility.