Mutilple reactions produces same serialized strings

[XRByte]

Currently, all reaction dictionaries are created from serialized strings. Since "special species" are not included in reaction parsing, such reactions are indistinguishable and previous reactions which produce the same serialized string are overwritten in the dictionary. These produces serious bugs during code generation

H -> H+ + e- 
H -> H+ + e- (photo-ionization)

# Serialized form, both produce the following
"H__H+_e-"

[XRByte]

Fixed in #103