this lets the caller not need to know the underlying sample rate. They
just ask for what rate updates happen.
This also changes the MPU6k filtering to be less than half the sample
rate
sanity checking added to accelerometer calibration routine.
user feedback is sent using gcs_send_text_fmt instead of Serial.printf.
moved ins parameters to new eeprom number to avoid conflicts with older parameters.
other small changes including renaming of functions and parameters.
Andrew Tridgell
rmackay9