Some test for Vector2d.

Where's a good testing framework when you need one?!
Behaviors can be empty and,

a heading equal to origin vector results in no moment. Yay!
Normalize the sum of heading and new-heading! Align-direction works.
Adhere-to-center works.

Premature optimization is the root of all evil.
WIP: maintain-separation. Added v/sum function.
Maintain-separation works. Clustering behavior check. A anachronistic map was still in the code.