_projectToAxis = function(projection, vertices, axis) {
        var min = Vector.dot(vertices[0], axis),
            max = min;

        for (var i = 1; i < vertices.length; i += 1) {
            var dot = Vector.dot(vertices[i], axis);

            if (dot > max) { 
                max = dot; 
            } else if (dot < min) { 
                min = dot; 
            }
        }

        projection.min = min;
        projection.max = max;
    }
Projects vertices on an axis and returns an interval.
@method _projectToAxis
@private
@param {} projection
@param {} vertices
@param {} axis