Revert "remove option to use deprecated cantera api"

This reverts commit ab15a7b.

Author: JacksonBurns

rmgpy/kinetics/arrhenius.pyx

@@ -232,11 +232,14 @@ cdef class Arrhenius(KineticsModel):
         """
         self._A.value_si *= factor
 
-    def to_cantera_kinetics(self):
+    def to_cantera_kinetics(self, arrhenius_class=False):
         """
         Converts the RMG Arrhenius object to a cantera ArrheniusRate or
         the auxiliary cantera Arrhenius class (used by falloff reactions). 
         Inputs for both are (A,b,E)  where A is in units of m^3/kmol/s, b is dimensionless, and E is in J/kmol
+
+        arrhenius_class: If ``True``, uses cantera.Arrhenius (for falloff reactions). If ``False``, uses 
+        Cantera.ArrheniusRate
         """
 
         import cantera as ct
@@ -266,7 +269,10 @@ cdef class Arrhenius(KineticsModel):
 
         b = self._n.value_si
         E = self._Ea.value_si * 1000  # convert from J/mol to J/kmol
-        return ct.ArrheniusRate(A, b, E)
+        if arrhenius_class:
+            return ct.Arrhenius(A, b, E)
+        else:
+            return ct.ArrheniusRate(A, b, E)
 
     def set_cantera_kinetics(self, ct_reaction, species_list):
         """
@@ -918,7 +924,7 @@ cdef class PDepArrhenius(PDepKineticsModel):
         assert isinstance(ct_reaction.rate, ct.PlogRate), "Must have a Cantera PlogRate attribute"
 
         pressures = copy.deepcopy(self._pressures.value_si)
-        ctArrhenius = [arr.to_cantera_kinetics() for arr in self.arrhenius]
+        ctArrhenius = [arr.to_cantera_kinetics(arrhenius_class=True) for arr in self.arrhenius]
 
         new_rates = ct.PlogRate(list(zip(pressures, ctArrhenius)))
         ct_reaction.rate = new_rates

rmgpy/kinetics/falloff.pyx

@@ -234,8 +234,8 @@ cdef class Lindemann(PDepKineticsModel):
         """
         import cantera as ct
 
-        high_rate = self.arrheniusHigh.to_cantera_kinetics()
-        low_rate = self.arrheniusLow.to_cantera_kinetics()
+        high_rate = self.arrheniusHigh.to_cantera_kinetics(arrhenius_class=True)
+        low_rate = self.arrheniusLow.to_cantera_kinetics(arrhenius_class=True)
         return ct.LindemannRate(low=low_rate, high=high_rate)
 
 
@@ -413,6 +413,6 @@ cdef class Troe(PDepKineticsModel):
             T2 = self.T2.value_si
             falloff = [A, T3, T1, T2]
 
-        high = self.arrheniusHigh.to_cantera_kinetics()
-        low = self.arrheniusLow.to_cantera_kinetics()
+        high = self.arrheniusHigh.to_cantera_kinetics(arrhenius_class=True)
+        low = self.arrheniusLow.to_cantera_kinetics(arrhenius_class=True)
         return ct.TroeRate(high=high, low=low, falloff_coeffs=falloff)