Make aromaticity instance extendable.
Aromaticity model for MMFF.
Provide access to several useful Aromaticity implementations.
Actually return MmffAromaticity instance.
The SMARTS degree is dependant on hydrogen representation. Attempting to compensate for this in the match is counter intuitive when matching of explicit hydrogens is actually needed (e.g. force field atom typing).
The SMARTS '*' should match any atom, include hydrogen. Hydrogen was not previously matched due to confussion over explicit-H matching in SMARTS.
MMFF atom typing based on SMARTS patterns. All molecules in the validation suite are assigned the expected symbolic type.