Alignment Behavior

Alignment Behavior and Cohesion Behavior added to security_behavior.js.

Trying to fix Alignment Behavior, I realized it wasn't pushing boids
into visible_object array because when called, there was three
parameters being passed to the method instead of two so heading was added
to the parameter list. Heading was added to take vision angle into
account but was never fully developed.

Also, projection from vector.js was returning an
array instead of a vector.

Therefore, when in Alignment Behavior, velocity couln't be substracted
from desired_velocity.

It was fixed by making what projection returns into a vector.
Merge branch 'feature/boids' of https://github.com/txemagon/lluvia-Project into feature/boids