Support external voltage and current sensor

configured via config.h

Increase PWM frequency on motor output pin

Sets PWM frequency to 32 kHz instead of 500 Hz -> removes ripple from
motor output

Modified speed calculation for slow speeds

Calculates the upper limit of the speed based on the time elapsed since
the last speed_change event.
If this upper limit is slower than the last real measurement, this
slower speed is used.

Move shutdown checks from slow loop to fast loop

New config option SUPPORT_MOTOR_SERVO

Uncomment SUPPORT_MOTOR_SERVO if you have an RC motor controller
connected to the motor output. Do not forget to remove capacitor from
the low pass filter of the motor output.

Fix Bug in shutdown sequence

Bug could produce 5V at motor output during shutdown

Fix torque reading

No more skipped interrupts due to cli() sei() commands before
analogRead.

Update outdated description

Ability to enable bluetooth on startup via config.h switch

Show clock instead of runtime if RTC is connected