function mulScalar(v, k, dst) {
    dst = dst || new VecType(3);

    dst[0] = v[0] * k;
    dst[1] = v[1] * k;
    dst[2] = v[2] * k;

    return dst;
  }
Mutiplies a vector by a scalar.
@param {module:twgl/v3.Vec3} v The vector.
@param {number} k The scalar.
@param {module:twgl/v3.Vec3} [dst] vector to hold result. If not new one is created..
@return {module:twgl/v3.Vec3} dst.
@memberOf module:twgl/v3