Add avogadro (Trac: #1510)

Per faculty (hjkulik) request for 10.437, add avogadro
Add BUILDING file for documentation

Fully document the list syntax in the BUILDING file, and update
the comment in lists/common to point there.
Add wordnet-gui (Trac: #1516)

This should have been added with the rest of the
packages in 78506732, but wasn't.