Dynamically sized heatmap

[andschneider]

The current sizing of the heat map doesn't display well on smaller sized terminals.

I think I need to calculate the size of the current terminal window and then change the size of the heat map accordingly. Additionally, there are 3 columns and 3 rows in the heat map, so the overall size of the heat map should be equally divisible by 3 (or just find closest number divisible by 3 for row and col size?).

[andschneider]

closed in PR #7