Enable property polimorphysm in individual statements

[GoogleCodeExporter]

Example:

first-name extends name. If we set :first-name of a person and ask for 
:name, we should get something (:name, :first-name, or some other combinatio 
of available data)

Original issue reported on code.google.com by draga...@gmail.com on 17 Mar 2010 at 2:56