Vertical points

Height <=> Depth reversal

$point = VerticalPoint::create(...);
$newPoint = $point->heightDepthReversal(
    Vertical $to
); // returns a new VerticalPoint

Vertical Offset

$point = VerticalPoint::create(...);
$newPoint = $point->verticalOffset(
    Vertical $to,
    Length $verticalOffset
); // returns a new VerticalPoint