Added trace lines to the hat in unit10-jaunty-hat demo

This creates a line that tracks the top of the hat, so we can see the differences between the quaternion and euler rotations more clearly.

I used ParticleSystem with a fixed number of vertices, and updated the last vertex every frame. It may look sort of weird. A solid line would be better, but I couldn't think of an efficient way to create a dynamic line. Maybe someone has a solution?

Live version: http://goo.gl/YCfOt