OHLC Chart

[neomantra]

Another common chart type is OHLC / Candlestick charts. We should add this chart type and adapt our sample to show either a line chart (current) or OHLC.

Here's some prior art:

• https://github.com/Julien-R44/cli-candlestick-chart
• https://github.com/BoboTiG/py-candlestick-chart