Added triangle drawing, and rotation, but the rendering of the rotation currently seems to be broken.
Fixed some silly bugs.
Seem to have figured out proper canvas management, so the flickering no
longer occurs. Something about the heading math still isn't consistent;
currently mod'ing by pi, but doesn't have the desired effect.
Slight refactoring, determined mod 2pi was the right approach, but still
boids don't fly right.
WIP: Debugging heading-to-radians and fixing draw-func to treat
positive x axis orientation as the default.
Calculate the angle of a vector. Progress?

TODO: tests for angle implementation.
Expanded and rewrote tests for angle
Discovered atan2, and all of our problems were solved. Triangles are now
directional and completely spiffy.