Fixed typo in rate rule

Made a typo in earlier commit for this family
Understand that multiplicity of '{2S,2T}' is equivalent to '2'.

This is when reading adjacency lists, and makes it more compatible with RMG-Py.
However, I think I'm about to make the database exporter export it as '2' anyway,
so this may not be necessary.
This is a belt-and-braces approach to solve @GreenGroup/RMG-database#18
Understand thermo trees that start at level L1 instead of L0.

I am not sure why the thermo trees used to start with L0
whereas the kinetics trees all begin with L1. In RMG-Py they
all begin at L1, which made exported things incompatible.
Now we try L0, if that fails try L1, and if that fails throw 
an exception.
Understand frequency trees that start at level L1 instead of L0.

Same story as previous commit.
Exporting things from the RMG-database project starts trees at level L1.
For some reason, frequency trees were expected to start at L0.
Now either will work.
Add rates to 1+2_cycloaddition and 1,2_insertion

Rates taken from Polino et al. Paper not available to public yet
so comment about its methods will be added later.

Also these the1+2_cycloaddition family does not really work
correctly without additional hard-coded changes. These are
still being tested.
Updating rate rule for CO2 elimination from methyl esters

Rate calculations for CO2 + C3H8 = methyl propanoate
by Aaron using BMK/CBSB7 without hindered rotors
Fixing typo in 1,3 CO2 insertion

Ea = 118.0 kcal/mol
Clossing aromaticity perception for generation of reactions

To allow species like cyclohexadienyl radical to go to benzene
we need the aromatic species to be represented by single-double
bonds.

However to get the correct thermo and transport properties we still
should convert it back to Cb representation. Currently we will just make
a copy of the graph and percive aromaticity on it to get the correct
thermo and transport properties.

Done with help of Aaron Vandeputte