Am I understanding this correctly that users can specify either `dimensions` or `min/maximumCorner` but not both at the same time?  (it also looks like we just ignore one if the other is specified).  If so, then we should have the constructor only take mix/max corner (since that seems to be with you want) and have a `BoxGeometry.fromDimensions` overload that takes a dimensions object.  This will make the API much cleaner.  You can always get rid of the options object at that point, since it will no longer be needed.