Fix bug in polycyclic thermo estimation
Fix bug in polycyclic thermo estimation

Apply ring corrections to ALL types of rings, polycyclic and monocyclic, instead of assuming there is one or the other.  

Previously, only assumed a single polycyclic ring.
Now, algorithm should be able to recognize mixed rings. Unit tests to follow.
chatelak/RMG-Py,chatelak/RMG-Py,nyee/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,pierrelb/RMG-Py,nickvandewiele/RMG-Py,nickvandewiele/RMG-Py