Implementation of commutation control.

The commutation calculation and control is more or less finished (for
now). The time is measured using the halGetCounterValue, which uses the
MCU clock cycle counter. This is a 32 bit counter running at 168MHz,
which means it will wrap ever 25sec. More than enough for timing the
commutations. This also means the entire BLDC is implemented using one
channel on one timer.

The functionality that is implemented so far is confirmed by measuring
with oscilloscope.

There is still no zero crossing sensing, nor any startup algorithm. The
RPM is hard coded right now.

Some code clutter has been removed, while some new is added.