src/algorithms/isomorhpism.h: Make references to molecules const.
Add RingSet::numRings(atom)
Fix get_valence(), add get_connectivity() and is_hydrogen()
Fix hydrogen handling for reading smiles
Test reading multi-component smiles (SMILES.SMILES)
Some bug fixes for smiley.h
Create doc groups for Alpha, Beta and Production code.
Add Smarts class.
Fix bug in relevant_cycles() + remove is_cyclic (replaced by RingSet)
Correctly overload molecule API for HeMol
Implement recursive SMARTS
Move non-template code from smarts.h to smarts.cpp