Automatic deduction of viewport size in jupyter

[bluescarni]

As discussed on gitter, here,

https://gitter.im/maartenbreddels/ipyvolume?at=5c656be5d1e3093ab51cbd40

when using the scatterplot in jupyter, the viewport size is not automatically adapting to the data limits (it can just grow but not shrink). It would be nice if the viewport by default adapted automatically to the data limits.