anchor: BezierCurve:evaluate
  Evaluate Bézier curve at parameter t. The parameter must be between 0 and 1 (inclusive).
  
  This function can be used to move objects along paths or tween parameters. However it should not be used to render the curve, see BezierCurve:render for that purpose.
  x, y = BezierCurve:evaluate( t )
  t number Where to evaluate the curve.
  x number x coordinate of the curve at parameter t.
  y number y coordinate of the curve at parameter t.