Updating tutorials

Description

The tutorial text files are updated. In addition, scripts are added, which can be run after the tutorial input files have been run, which generate the snippets of the outputs, which are included in the tutorials.

The generated txt files are stored in the octopus/doc/tutorials/ folders and are part of the repository, so that the documentation can be generated without the need to rerun all tutorials.

When the code, or tutorials have been modified so that the results change (significantly), the corresponding tutorials need to be re-run and the snippets regenerated with the tutorials.sh script.

News snippet

Update tutorials and introduce semi-automatic generation of output snippets

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.