Notebook illustrating use of compact out files

[znicholls]

Is your feature request related to a problem? Please describe.

At the moment we have compact out readers but no docs about how to use these files (#277).

Describe the solution you'd like

Once MAGICC7 is released, add a notebook showing how to use these files for maximum speed with MAGICC. Would be great to include a parallel MAGICC option at the same time (which results in big speed improvements).

Describe alternatives you've considered

Add the notebooks without MAGICC7 being available, is a bit pointless really.

Additional context

Add any other context or screenshots about the feature request here.