This is for exploring basic movement motivation and explores questions such as
the following:
 * How to two attrated entities approach each other?
 * How about entities with differing levels of attraction?
 * What about repulsion?

First Steps
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If we create two entities and assign them equal "coefficients of attraction",
they should move towards each other with equal distance over time.

If we create two entities, one with a greater "coeeficient of attraction", for
every unit of time increment, they should move towards each other a distance
proportional to each entity's coefficient of attraction.
