Added more attributes to the solidsolution class
Merge branch 'add_thermodynamic_potentials' of https://github.com/burnman-project/burnman into add_thermodynamic_potentials
Rejigged SolidSolution class
Added check for endmember and solid solution member compositional equality
Added solid solutions from hefesto to new SLB_2011 input file
Documented and changed name of sample_pressure (now eos_pressure)
Re-removed comments in mineral classes
Moved molar_mass.py to misc/
Changed comment blob for burnman.SolidSolution
Solid solutions in SLB2011 given full names and abbreviated aliases