Guidebook update and SEDUCE runtime switch

add SYSCF docs to the Guidebook because it's info needed in a binary distro
Guidebook.tex - also add some missing italics to some "NetHack" occurances
call nethack.org "official"
Guidebook.txt - didn't regenerate cleanly so no diff
add SEDUCE to SYSCF (only partly inspired by the recent email)

include/config.h

@@ -161,6 +161,7 @@
  *		ENTRYMAX	(max entries in the record file)
  *		POINTSMIN	(min points to get an entry)
  *		PERS_IS_UID	(0 or 1 - person is name or (numeric) userid)
+ *		SEDUCE		(0 or 1 - runtime disable/enable SEDUCE option)
  *
  *		The following options select how the config space is stored:
  *		SYSCF_FILE	in the named file

include/extern.h

@@ -2118,6 +2118,12 @@ E int FDECL(add_sound_mapping, (const char *));
 E void FDECL(play_sound_for_message, (const char *));
 #endif
 
+/* ### sys.c ### */
+
+#ifdef SYSCF
+E void FDECL(sysopt_seduce_set,(int));
+#endif
+
 /* ### sys/msdos/sound.c ### */
 
 #ifdef MSDOS

include/sys.h

@@ -29,8 +29,15 @@ struct sysopt {
 	int panictrace_glibc;
 # endif
 #endif
+	int seduce;
 };
 E struct sysopt sysopt;
 
+#ifdef SEDUCE
+# define SYSOPT_SEDUCE sysopt.seduce
+#else
+# define SYSOPT_SEDUCE 0
+#endif
+
 #endif /* SYS_H */