Adjusted A factor in H_Abstraction rule #75.

The previous A-factor was orders of magnitude larger than other A-factors
from the Saeys rules. We attempted to use the Saeys group values to
estimate the correct value, and got a number far closer to 3e12 than
3e18. This is also much more consistent with an estimate from Tsang (in
the NIST database).
Merge in Abraham data estimator fixes.

Some changes to the stand-alone class for estimating Abraham parameters,
an example input file and shell script to run it,
and some changes to the group definitions and library values taken from
Amrit's autoxidation_rebased branch. Overall, this should now reproduce
the data reported in http://dx.doi.org/10.1021/jp310824h