Zero data and minBarHeight=0 breaks multiple columns in BarChart

# 🐛Bug report

**Describe the bug**
When multiple columns are supplied for a `BarChart`, and `minBarHeight={0}` is used, then the first column that has `0` data will stop later columns rendering.

This happens because [this line of code](https://github.com/esnet/react-timeseries-charts/blob/master/src/components/BarChart.js#L274) should `continue`, not `break`.

**To Reproduce**
#364 has a good example that produces this.

**Expected behavior**
Even when one bar is zero height, the other bars should render still.

**Desktop (please complete the following information):**
- OS: MacOS 10.14.6
- Browser Chrome
- Version 75.0.3770.142 64-bit

Start in src/components/BarChart.js at the linked line around 274 and compare the behavior with the reproduction described in issue #364. Change the handling so a zero-height bar does not prevent later columns from rendering, then verify that all subsequent bars appear when minBarHeight={0}.

Written by the indexing model from the issue text.