Lots of MacTCP networking stuff. I think all the code's written, but it

doesn't actually work yet.  Also the telnet backend is still single-session,
and I haven't even touched the ssh one.  Oh, and the "Main" segment just
overflowed 32k, so we have extra linker incantations.  I'm off to the pub
now.

[originally from svn r156]

mac.h

@@ -30,6 +30,8 @@ extern void mac_keyterm(WindowPtr, EventRecord *);
 extern void mac_menuterm(WindowPtr, short, short);
 /* from maccfg.c */
 extern void mac_loadconfig(Config *);
+/* from macnet.c */
+extern void macnet_eventcheck(void);
 
 #endif