fix bug in delay_until and disable emulation
calibrate scale

Note that calibration using only integers (and long) does not work very
well. It seems as if we need floats. Measurement works for <20g quite
well (about -/+1g) but not at all for >100g. I assume this is simply
because I had to round the ADS1231_DIVISOR.
fix turn_until function

We cannot check the weight after each servo step, it slows down the
servo.
adjusting many config parameters

This are live tested values, but still not perfect.
add some debug msgs and some more debug code