K-Box Firmware - #89 IMUMonitorPage and some config settings

[rgleason]

Every once in awhile something gets your attention for some reason, but I found this K-Box PR interesting

https://github.com/sarfata/kbox-firmware/pull/89

Now the concept is: the values for the monitorPage are triggered by updateReceived(const SKUpdate& up)
which means the updates are coming by the interval of the imuService.
In the IMUPage would be the filter and a elapsed time thing for bringing down the values to display-frequeny.
Just thinking of: would it be better to make the display of data (at least the Voltage, Baro, IMU, may be wind and other pages) an interval task?
This would mean, that the filter would be in the IMUService (which would be there anyway if you might switch to a better IMU sensor for future KBox Hardware releases e.g. this one: https://www.adafruit.com/product/3463 which has no integrated fusion as the BNO055)
The other advantage of filtering in high frequency is to get out noise without visual time delay. (which we certainly have at low frequencies, you can see it quite a lot in openCPN!)
The Page loop would then just call an actual value for the display (completely independent from the Service-frequency.) Same for different other (low speed) outputs....
The other things:

1. config settings will change as discussed
2. two Service defines added.
   The aim is, that users could define their services needed for a special hardware.
   E.g. it would then be possible to comment out several services to make a logging device with a T3.2 or 3.6 + CAN without display, wifi, baro, imu
   Or just to switch off Baro and IMU if not needed and so on....
   Or with a special (less equipped and lower priced) KBox as N2k->NMEA0183 Serial/WiFi-converter.

Would you like this?

Then looked at
Adafruit Precision NXP 9-DOF Breakout Board - FXOS8700 + FXAS21002 PRODUCT ID: 3463 $14.95

and then the specs
https://learn.adafruit.com/comparing...ope-datasheets

and learned some things. It keeps moving. I used to think the MPU-9250 was good, but had no understanding or knowledge why.