lerp( v, alpha ) {

		this.x += ( v.x - this.x ) * alpha;
		this.y += ( v.y - this.y ) * alpha;
		this.z += ( v.z - this.z ) * alpha;
		this.w += ( v.w - this.w ) * alpha;

		return this;

	}
Linearly interpolates between the given vector and this instance, where
alpha is the percent distance along the line - alpha = 0 will be this
vector, and alpha = 1 will be the given one.

@param {Vector4} v - The vector to interpolate towards.
@param {number} alpha - The interpolation factor, typically in the closed interval `[0, 1]`.
@return {Vector4} A reference to this vector.