Merge pull request #14 from cider-team-mercury/energetics

Changed iterative procedure to start mantle temperature at the core mant...
Merge pull request #15 from cider-team-mercury/energetics

pusing to ask for help with derivative dR_icb/dT_cmb
Fix Splines
Added Mantle Melt Models and conductive heat profile in stagnant lid
Added gradient at the base of the stagnant lid, the rate of crustal growth, and degree of melting in the stagnant lid
Calculate Stefan Number
Calculate growth of stagnant lid
Small bugfixes
Rewrite melt degree function
Some tests
Pushing to be sure
Fix stuff
added smoothing to spline function fit in mercury_interior_structure_model.py
merged and added additional functions to the dumberry model so that it can check which side of the eutectic it is on