The API for describing the interaction between application and non-application classes.

The Resolver and ExternalVisiblity interfaces may be implemented by clients to assist the analysis.

This code may be used under the terms of the GNU General Public License. @author Anders Møller <amoeller@cs.au.dk> @author Aske Simon Christensen <aske@cs.au.dk> @author Asger Feldthaus <asf@cs.au.dk>