bool OEAtomIsInRingSize(const OEAtomBase &atm, unsigned int size)
Determine whether the given atom is in a cycle of the specified size.
The function OEFindRingAtomsAndBonds
should have been called before
calling this function. If the atom is not in a ring, i.e.
OEAtomBase::IsInRing
returns false, then this function also
returns false. This function returns false for all values of size less than
three.