Added Antimony model. Added export non-mass action kynetics rate to tutorial

Author: fabriciocravo

docs/example_models/journal_models/Antimony_Comparison.py

@@ -0,0 +1,13 @@
+from mobspy import *
+
+Replicator, Mortal = BaseSpecies()
+Replicator >> 2*Replicator [lambda r: 2*(100 - r)*r]
+Mortal >> Zero [1]
+
+A, B, C = New(Replicator*Mortal)
+A + B >> C [1]
+
+S = Simulation(A | B | C)
+print(S.generate_antimony()[0])
+
+