Each cell has a vitality score from 0 to 6.
A cell lives, dies, remain the same or increase it's vitality depending on the sum of the 8-neighbors vitality.
Current constants:
const MAX_VITALITY = 6
const OVERPOPULATION = 7 * MAX_VITALITY
const UNDERPOPULATION = 2 * MAX_VITALITY
const GROW_THRESHOLD = 0.48