lerp = (out, a, b, t) => {
  const ax = a[0]
  const ay = a[1]
  out[0] = ax + t * (b[0] - ax)
  out[1] = ay + t * (b[1] - ay)
  return out
}
Performs a linear interpolation between two vectors.

@param {vec2} out - receiving vector
@param {vec2} a - first operand
@param {vec2} b - second operand
@param {Number} t - interpolation amount between the two vectors
@returns {vec2} out
@alias module:modeling/maths/vec2.lerp