[FEATURE] Sensor calibration

[MB3hel]

IMU:

• Ability to calibrate IMU, read calibration registers, store that persistently on a single device, and write the calibration registers on each startup.
• Would also likely need a way to read calibration status of each sensor.
• The BNO055 may be able to save a calibration profile? Need to check datasheet.

Depth sensor:

• Ability to indicate a "surface" reading as "zero" depth. Ideally also could be stored and re-applied on each startup (not on the depth sensor itself, but in firmware).
• Ability to change surface atmospheric pressure and fluid density constants directly

[MB3hel]

Now WIP on feature/imucal branch. Using emulated eeprom to store calibration data (see feature/emueeprom).

[MB3hel]

BNO055 calibration now functional on the feature/sensorcal branch.

[MB3hel]

Fully implemented on feature/sensorcal