Support 'autorun: true' code blocks

[HenrikBengtsson]

This address Wish 2 of Issue #19; make code blocks with autorun: true automatically run.

PS. I release my copyright claims to this addition, so you have full control of the license etc.

[coatless]

Hey Henrik, thanks! I'm a little preoccupied with a few things right now; but, I have a library revamp on my agenda for the 1st week of February. I will tackle this contribution then if that's okay?

There's a few fun things going on behind the scenes.

(cf https://apps.apple.com/us/app/webrios/id6758071087)

[HenrikBengtsson]

I totally understand. I've applied these two patches to our online demo https://www.seguid.org/demo-python.html - so we're good for now. BTW, I was looking into using 'quarto-live', but I noticed that the startup time for R was more than twice as long (8-10 seconds instead of 3-4 seconds), because of other packages being loaded. Didn't check Python. Anyway, you're implementation here still have leverage. I should also wish to say thanks for this great work of yours.

Nice iOS app there; I can imagine it must be particularly tricky on that OS. (I'm on Android). Looking forward to hear about your releases later on.