pipictest small clean up
pipicswd.c clean up code

Separate shared code segments for logmessage, writecmd, readdata and
testi2c routines.
pipichbd.c add 'go' and 'set' commands to set position

The command 'go N' calculates time needed to turn the DC motor to reach
a given position N. This method is not very accurate and depends how
well the motor rotation speed is known.

The command 'set N' moves motor first close to final position and then makes
small corrections if necessary.