Material model based on tomography data or table properties

[alarshi]

This PR adds the material model we (@gassmoeller , @jdannberg ) have been using for our global mantle flow models. All the relevant input files and the prm file we want to use for a cookbook are in relevant folders.

Before your first pull request:

• [x] I have read the guidelines in our CONTRIBUTING.md document.

For all pull requests:

• [x] I have followed the instructions for indenting my code.

For new features/models or changes of existing features:

• [x] I have tested my new feature locally to ensure it is correct.
• [ ] I have created a testcase for the new feature/benchmark in the tests/ directory.
• [ ] I have added a changelog entry in the doc/modules/changes directory that will inform other users of my change.

[bangerth]

Will review after dinner. If you want to make sure that the indentation is correct before I get to it, that'll be fine too.

[jdannberg]

@alarshi I commented on all the points that you did not resolve and that seemed complicated. I hope that is enough information for you to finish this PR. If not, let me know!

[alarshi]

Something went wrong during the rebase. Closing this pull request to see if reopening fixes the github changes page.