Improve formating of values in basal and bolus tooltips:
- suppresses floating point inaccuracies in demo data
- formatting works as follows:
   - up to 3 units of precision allowed (e.g., 1.875, 0.875)
   - but 0-padding on the right is truncated to one decimal of precision (e.g., 1.0 instead of 1.000)