Some more work with ring coordinates generation.
Some more work with ring coordinates generation.

We should be able to handle some more complex ring systems, although still
not any with bridging atoms, and still not in functional groups. In particular,
mixing of ring sizes should hopefully be handled a bit more sensibly.

faribas/RMG-Py,pierrelb/RMG-Py,comocheng/RMG-Py,chatelak/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,comocheng/RMG-Py,nickvandewiele/RMG-Py,enochd/RMG-Py,KEHANG/RMG-Py,faribas/RMG-Py,jwallen/ChemPy,enochd/RMG-Py,KEHANG/RMG-Py,nyee/RMG-Py,chatelak/RMG-Py