Evaluation is now in non-stochastic environment

Now, instead if selecting the light source position randomly each
time an individual is evaluated, the evaluation consists of testing
the individual against four predetermined light source positions
and taking the minimum result.

This commit is intended to save the state of the program during
a particular evolutionary experiment (see https://docs.google.com/
document/d/1MLPGYKzeDlH042ZWT6AX8W2v78-eZMMQvpmCfxUzMvg/edit?usp=sharing).