Tweak to species constraint allowed molecule list.

I'm not 100% sure we've generated resonance isomers at this point,
so this change may not be enough, but I feel we should allow all resonance
forms of an allowed species.
Trying to refactor enforceSpeciesConstraints in CoreEdgeReactionModel

Trying to reduce code duplication.
My idea was to have a function that enforces the species constraints,
and pass this function in to the family reaction generation routines,
rather than passing in the dictionary of constraints and having the
checks be done in two different places.

I'm not sure it's going to be very elegant though, and is currently broken...
(committing now before I forget).