Added INITIATOR_TEST and RESPONDER_TEST macros to the identity hiding
mpv file that can be used to selectively test the anonymity of the
initiator or the responder.
Changed identity hiding test to work as a two stage process where
participants with fresh secure secret keys communicate with each other
and other compromised participants. Then the attacker is asked to
identify the difference between two of the secure participants as on of
them acts as a responder.
