Create a Bangle.isWorn() method

Hi,

I was using https://banglejs.com/apps/?id=health for a day until I realized that it doesn't stop HRM when I stop wearing it at night.

see edit below
Regarding Bangle.getHealthStatus().movement > 146: from the docs,
movement is the sum of diffs, so you can't just use a constant
threshold. And as Gordon pointed out, it only resets every 10min.

Anyways, Bangle.js already detects movement for powerSave option and for me this would be sufficient. The following proof-of-concept works well enough for me:

function is_worn() {
    return new Promise(function(resolve, reject) {
        var i = 0;
        function on_accel(a) { i++; }
        Bangle.on('accel', on_accel);
        setTimeout(function() {
            Bangle.removeListener('accel', on_accel);
            resolve(1 < i);
        }, 3*80);
    });
}

I didn't find a way to get the current power state/poll interval/"hasn't moved". Is there?

edit: I was wrong, acceleration diffs are unsigned, sry