Full model implementation

This is a pre-alpha release representing the full model, with multicomponent mobility implemented. The implementation suffers from poor performance and, critically, "shoulders" in the field variables through the interface: the free energy is likely compromised, but the issue has not yet been resolved.

Please refer to this codebase for reference and differential analysis. The main reason for "releasing" is to trigger an updated Zenodo build, not as an indication of suitability for any purpose. Happy coding.

Zenodo integration

The purpose of this release is to trigger generation of a new DOI on Zenodo, which will make phasefield-precipitate-aging citable.