Fix & Test adjustToNeighbour

I need to write tests for pushing the boid in each of the four quadrant
directions to make sure all the +/- work out.
Test pushing a boid towards Q2

i.e. if the neighbour is below and to the left and is only %50 of the
required range away from the boid, then the boid needs to go 100% of the
distance between them up and to the right, i.e. (x1 - x2), (y1 - y2)
Test adjustToNeighbour pushing towards Q2 & Q4