Derivatives added, need tests now:
  - eddy diff eval
  - mol diff eval
  - diff eval
  - atm mixture, atmospheric scale height
  - atm kin eval
  - physics eval

binary is finally useless for the calculations, but it can't hurt
to have it tested too
Merge pull request #3 from SylvainPlessis/planet_grins

Derivatives added, need tests now: