Some experiments with ADC processing.
ADC synchronization removed, sampling interval set to 8us (continuous conversion mode). There are some stability issues (especially during intensive duty cycle changes), but this can be fixed with fine tuning so not a problem.
Hovewer, there are two real problems:
1. The motor still seems to stick around the stable RPM values (where the comm period is a multiple of half PWM period).
2. Unsynchronized ADC will not perform well with complementary PWM.
Revert "Some experiments with ADC processing."

This reverts commit 3d69032a9498b24de861b3704c6e82dac72b80cd.