Add Face Size To Fitness

Add size of face to fitness, thereby favouring larger faces. For example, line 343 could be changed from
"this.fitness = comp[0].confidence;"
to
"this.fitness = comp[0].confidence * ((comp[0].width * comp[0].height) / (CANVAS_SIZE * CANVAS_SIZE));"
This would scale the fitness based on the size of the face, thereby favouring larger faces with the same score as smaller faces. There is probably a better way to implement this.