Generate more representative demo data

It’s nice to showcase demo data on [autodesk.github.io](https://autodesk.github.io/hubble/), even if it’s generated. In this way, users can get a feeling for new features such as the multiview charts.

However, some demo data files are very small and not very representative for demonstrating the use of multiview charts, for example. Hence, it would be great to have more extensive demo data files so that everything looks nice on the interactive live demo.