adding parameter for recombination term in neutrinos

[khanakbhargava]

No description provided.

[khanakbhargava]

[zingale]

if I run with and without this contribution I likewise see that the effect of this term is minimal:

            variable name            absolute error            relative error
                                        (||A - B||)         (||A - B||/||A||)
 ----------------------------------------------------------------------------
 level = 0
 density                                          0                         0
 temperature                                      0                         0
 X_hydrogen-1                                     0                         0
 X_helium-3                                       0                         0
 X_helium-4                                       0                         0
 X_carbon-12                                      0                         0
 X_nitrogen-14                                    0                         0
 X_oxygen-16                                      0                         0
 X_neon-20                                        0                         0
 X_magnesium-24                                   0                         0
 X_silicon-28                                     0                         0
 X_sulfur-32                                      0                         0
 X_argon-36                                       0                         0
 X_calcium-40                                     0                         0
 X_titanium-44                                    0                         0
 X_chromium-48                                    0                         0
 X_chromium-56                                    0                         0
 X_iron-52                                        0                         0
 X_iron-54                                        0                         0
 X_iron-56                                        0                         0
 X_nickel-56                                      0                         0
 X_neutron                                        0                         0
 X_proton                                         0                         0
 sneut                                        68512            2.06322307e-19
 dsneutdt                           2.919137478e-05           1.002638445e-19
 dsneutda                                   47107.5           2.937855096e-16
 dsneutdz                                    267723           1.460945619e-15