Updating the forbidden group in Intra Diels Alder reaction

It should now not allow any of the benzene substitutents.
However I think it will still fail on other aromatics like
naphthalene and anthracene. I am not sure what would be a
general solution right now. Since it is a special family
to form aromatics in pyrolysis -- I might turn this family off
by default for now.
Changing the default setting to off for Intra_Diels_alder2
family for now.

This family causes RMG to break everytime it encounters an aromatic
ring not in its forbidden group list. I am not sure should we come with
a comprehensive forbidden group list or hard code a fix in the code?