demo day commit, without actual reading

Unfortunately, these is a huge commit, because .gitignore is a little
bitch and won't listen.  This build changes the arrow color based on
three sensors, displays a message after a significance level, and also
makes you change cars (with message) after a certain number of
checkpoints.  It takes the sensore data from a LOOP.  NOT the real
thing.  Please correct the few lines necessary in PipeReader and
DemoBehavior (the latter needs appropriate channels also).
further commit?