Added fictitious transport group for R=C=R in a ring.

Without this existing, things like 1C=CCCC=C1 crash.
Not sure what its value should be.
Add comments to transport groups databases.
Added triple bond in a ring to the transport group estimates database.

Had to invent the numbers (copied C=C in a ring).
Change units of polarizability in transport libraries.

These are in fact "polarizability volumes" in units of Angstrom^3