Band Charts does not support TimeRangeEvent series

[tenzo]

🐛Bug report

Describe the bug The documentation states that BandCharts do support Indexed and TimeRange events in first scenario (when bands are passed within a series) and with Time events in second scenario (where bands are computed). But TimeRange events just don't work. To Reproduce

1. Create a series containing TimeRangeEvents
2. Observe bands are not being drawn.

Expected behavior Bands are drawn properly.

Desktop (please complete the following information):

• OS: Ubuntu 18.04
• Browser: Chromium
• Version 78.0.3904.70

Additional context I fixed the issue by modifying getSeries function in BandChart.js with following code:

        var ee = null;
        if (series._collection._type === _pondjs.TimeEvent) {
            ee = new _pondjs.IndexedEvent(e.index(), d);
        } else if (series._collection._type === _pondjs.TimeRangeEvent) {
            ee = new _pondjs.TimeRangeEvent(new _pondjs.TimeRange(e.begin(), e.end()), d);
        }
        return ee;

But I'm not a frontend dev so not sure if made it right way and I won't open the PR.