Have a scrollable container

[jviereck]

When having a bunch of TimeSeriesViews on top of each other, it would be great to have a scroll bar to go through all of them. This issue is about implementing such a container that has a scroll bar once there are more children than it has space for.

A possible first implementation could assign a fixed height to all children (height can be set via a property). This would make the layouting process easier.