Automatic transitions

[firebus]

I'd like the slideshow to run unattended. With the help of https://stackoverflow.com/questions/951021/what-is-the-javascript-version-of-sleep I kludged it in like this in slides.js:

    function sleep (ms) {
        return new Promise(resolve => setTimeout(resolve, ms));
    }

    async function transition(ms) {
        while(1) {
            await sleep(ms);
            console.log('wake up')
            nextSlide();
        }
    }

    // initialize

    (function() {
...
        transition(2000);
    })();
}

[firebus]

Oh, and I also made nextSlide() wraparound from the last slide to the first:

    var nextSlide = function() {
        if (currentSlideNo < slides.length) {
            currentSlideNo++;
        } else {
            currentSlideNo = 1;
        }
        updateSlideClasses(true);
    };