#1294 Aromaticity problem in CDKHueckelAromaticityDetector

[Patrik Rydberg]

the atoms in the five ring of isoindole are not correctly perceived when using the smiles below are not recognized as being aromatic and having aromatic bonds. (Tested with CDK 1.4.8)
c2c1ccccc1cn2
a molfile of the same molecule with explicit double and single bonds is correctly perceived
and a smile with explicit bonds as well
C2=C1C=CC=CC1=CN2

[John May]

Fixed - SMILES parsed in > 1.5 throws an exception for non-kekulisable molecules.