static midpoint(vecA, vecB) {
    return new Vector2((vecA.x + vecB.x) / 2, (vecA.y + vecB.y) / 2);
  }
Returns the midpoint of a line spanned by two vectors.

@static
@param {Vector2} vecA A vector spanning the line.
@param {Vector2} vecB A vector spanning the line.
@returns {Vector2} The midpoint of the line spanned by two vectors.