reduce white space / more compact design

[nandaloo]

Screen space is always scarce, even more for our tool where users create potentially many view and want to see them in parallel. However, the layout of the views uses a lot of white space.

To fix:

• reduce white space around views
• check UI for other components that unnecessarily consume a lot of space. Here the top task bar is worth a look. In particular, we could consider a different workflow / UI for creating new views alltogether (see also missing information on selected model and plot type #75 )