Added a test to mercury_minerals for comparing dT/dP of adiabats and melting curves. Found that the interpolated liquidus curve in liquidus model is unsuitable in its present state for consistent detection of iron snow. Also compared Fe melting curve of anzellini to adiabats calculated for 'high' and 'low' thermal expansivities of Williams 2009. Unable to reproduce curves of similar slope to williams. Also added the dumberry liquidus which is a linear interpolations between a eutectic and the anzellini melting curve.
Merge branch 'gravitational_energy' into merge_with_grav
Merge pull request #13 from cider-team-mercury/merge_with_grav

Merge with grav