Added solid iron shear modulus and calculated profiles
Merge branch 'master' of https://github.com/cider-team-mercury/mercury into latex_materials
changing reference radii to kilometers
Changed shear modululs to the values used to generate the profiles
Merge pull request #23 from cider-team-mercury/latex_materials

Added elastic profiles, with shear modulus used to generate them (from MaO et al. 2001)