Renamed variable to conform better to what it is in the model doc
Merge pull request #3 from SylvainPlessis/planet_grins

Derivatives added, need tests now:
Capture balanced neutral_species input
Merge branch 'enable_grins' of github.com:pbauman/Planet_INC into enable_grins
Merge pull request #4 from SylvainPlessis/planet_grins

Introduced bugs fixed, worst is the infinite loop, others
Merge branch 'enable_grins' of github.com:pbauman/Planet_INC into enable_grins
New formulation for diffusion

ns * omegas = A * dns_dz + B * ns
Merge branch 'planet_grins' of https://github.com/SylvainPlessis/Planet_INC into planet_grins