Collapse sensor data into a HUD element

[loudnate]

Taking cues from an early modification by @CrushingT1D, putting the last glucose value into a HUD element (I think I prefer second-from-leading).

Compactly this can describe the last glucose value, the trend arrow, the calibration state and the time, enabling the further removal of the text-based rows at the bottom that cause so much anxiety.

[jlucasvt]

This would be a great addition. I have found that adding this to the HUD is very helpful when using Loop. I am assuming Loop status would continue to be leading.