3. made shortcut at shutdown so that you don't get a storm of PC21s on busy
nodes as each connection goes down. Just send a pc39 to each interface and
nothing else.
+4. changed action of SIG{INT} and SIG{TERM} so that they now work on MSWin32
10Apr01=======================================================================
1. altered PC21 logic somewhat to eliminate dup PC21s
2. disconnect should remove dangling local users in the routing table.