Add another testcase, add lookahead-warmup.

Lookahead-warmup = two lines of G-code which take just long enough
to allow the intended movements to be added with look-ahead.
Add a draft of a script running testcases in SimulAVR.

This script also asks SimulAVR to generate pin traces of the X
and Y axis and even processes this data into a data file with
time, position and current speed of each axis.

Missing:

- Acceleration calculation.

- LOTS of polish.