Add support for Freestyle Libre 3

[isotherm]

The Libre 3 reports results in a different way:

• The history reports are missing a column of unknown meaning.
• The reading reports are missing custom comments and error values.

The workaround in this pull request manipulates the Libre 3 results to look like the results for earlier models and is for demonstration and documentation purposes only. A better implementation would abstract the difference in reporting format into the drivers for each device.

This pull request is meant to start discussion on the changes, the best way to accomplish them, and also eventually to produce documentation for glucometer-protocols

[isotherm]

Here are two sample lines from $history?:

243,12,1,11,25,10,23,43,1,0,0,0,85,60,0
233,12,1,11,25,10,18,44,1,0,0,0,0,55,32768

Here are two sample lines from $arresult?:

7429,2,1,13,25,20,22,12,1,2,0,0,88,1,3,1,1,1,1,1,0,3,4,0,1,3,0,3538,7,1,13,25,20,22,12,1,2
7415,2,1,13,25,20,15,47,1,2,0,0,93,1,3,0,0,0,0,0,0,3,0,0,0,0,0,3532

The first entry was marked with all checkboxes, and with entries of 1 unit rapid-acting insulin, 2 units long-acting insulin, 3g carbs (also 1hr and 2hr reminders), exercise, medication.

[sockpuppet42]

Can confirm that with this patch applied and --driver fslibre3 I can get useful looking values out of my fslibre3 (instead of a python-stacktrace with Key error: rapid-acting-flag).

[isotherm]

Would you mind telling me what device do you use to be able to read the sensor with the pc? thanks

There is a "FreeStyle Libre 3 Reader" device which reads the sensor. This change allows a PC (or really any device) to communicate with the reader over USB and download the readings. So the PC isn't reading the sensor.