Increase number of significant digits and/or make them controllable

[neubig]

Zeno rounds metric values to two decimal places before displaying them. This might be a bit too aggressive (usually there are 3 or 4 significant digits reported in papers).

I also think it might be a good idea to do rounding right before we print any numbers, but not before we create figures. I can't think of any reason to reduce the granularity of bar height for example.

We could consider:

• Making the default 4 instead of 2
• Making this value controllable through ZenoOptions
• Make rounding happen right before text is printed, but don't apply rounding when determining other things like bar height in a bar chart

Below is a specific example where rounding to significant digits is locking in the height on visualizations:

[Sparkier]

#868 Fixes the third bullet but we should keep this open for the other two.

[neubig]

Thanks for the quick PR @Sparkier! Actually for the third bullet, on bar charts (or other similar charts) it'd be nice to round the textual labels but not lock in the bar height. The labels are a bit verbose now:

[Sparkier]

Thanks for the quick PR @Sparkier! Actually for the third bullet, on bar charts (or other similar charts) it'd be nice to round the textual labels but not lock in the bar height. The labels are a bit verbose now:

Should be fixed in #869