Implement sensitivity for SurfaceReactor

This adds a Jacobian function (the same one copied over from SimpleReactor) so that we can run get sensitivities from a SurfaceReactor

Author: sevyharris

rmgpy/solver/base.pyx

@@ -714,7 +714,8 @@ cdef class ReactionSystem(DASx):
         if sensitivity:
             time_array = []
             norm_sens_array = [[] for spec in self.sensitive_species]
-            RTP = constants.R * self.T.value_si / self.P.value_si
+            if not self.constant_volume:
+                RTP = constants.R * self.T.value_si / self.P.value_si
             # identify sensitive species indices
             sens_species_indices = np.array([species_index[spec] for spec in self.sensitive_species],
                                                int)  # index within core_species list of the sensitive species