mr_server.h, qrtn.pc: punt get_client and change find_member to take a
struct client, and compare against both the users_id and the
client_id, so USER foo is recognized as being KERBEROS foo @ the local
kerberos realm.
qaccess.pc: use new find_member interface. also, add code in
access_list and fix existing code in access_member to allow kerberos
principals to glom, gaus, dmfl, and amtl [to public lists] themselves.