Is perpendicular and is parallel

[PlebusSupremus1234]

In this PR, I added two new methods: isParallelTo and isPerpendicularTo.

As the names suggest, they check whether the vector is parallel or perpendicular to another vector.

[cubedhuang]

the current code will always return false unless vec2.y === Infinity

the better way to do this and avoid division:

if you put the vectors as columns of a matrix, the columns are parallel if the matrix is linearly dependent, so we can just check if the determinant of the matrix is 0. this gives x1 * y2 - x2 * y1 = 0 which can be rewritten as x1 * y2 = x2 * y1. this also covers the edge case you have at the top because multiplying by 0 will just give 0.

Suggested change

	if (vec2.x === 0) return this.x === 0;
	if (vec2.y === 0) return this.y === 0;
	var kx = this.x / vec2.x;
	var ky = this.y / vec2.y;
	if (kx !== ky || ky !== 0) return false;
	else return true;
	return this.x * vec2.y === this.y * vec2.x;