system-wide configuration file

Add options SYSCF (to add a system-wide configuration file) and SYSCF_FILE
(for a file-based implementation of SYSCF) - this allows a binary distribution
to be configured at install time.  The only option supported at this time is
WIZARDS - a list of usernames which can use -D; currently only for unix-likes
but should be extendable to anything that has a concept of multiple users.
Add mac tty multiuser config using sgid.

include/decl.h

@@ -199,6 +199,9 @@ E const char *occtxt;			/* defined when occupation != NULL */
 E const char *nomovemsg;
 E const char nul[];
 E char lock[];
+#ifdef SYSCF
+E char wizards[];
+#endif
 
 E const schar xdir[], ydir[], zdir[];