ACTION 165 (Investigate easy keys in dl-lite)

Hi Ian, hi all,

easy keys can be included in DL-Lite without affecting the  
computational properties of the fragment, provided all the (data and  
object) properties that are included in a key assertion satisfy the  
same syntactic restriction that already holds for properties that are  
involved in functionality assertions.  Namely, such properties cannot  
be specialized.
So, easy-keys fit quite well within DL-Lite.

- Diego