Fix missing ground connection

The Magician's Chassis required a second ground connection for the
other side of the H-bridge
Improve line following algorithm

Increase the seek speed to avoid the motor binding up during its turn
and stopping the robot.  Generalize seek to make it easier to replace
the behavior for going left or right.
Merge branch 'master' of https://github.com/tamlicke/funwitharduino_intro into tamlicke-master

Conflicts:
	class_4/Magicians_Chassis.fzz
	class_4/Magicians_Chassis.jpg

	modified:   class_4/Magicians_Line Follower.fzz
	modified:   class_4/Magicians_Line Follower.jpg
	modified:   class_4/Magicians_Line_Follower/Magicians_Line_Follower.ino