edit: Report sector loss and gain properly for key 'L'

Send bulletin to owner and report news exactly like for key 'o'.

Also print a "sector duplicated" message, just for consistency with
other keys.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

include/prototypes.h

@@ -384,6 +384,8 @@ extern void stop_service(void);
 /*
  * src/lib/subs/ *.c
  */
+/* actofgod.c */
+/* in actofgod.h */
 /* askyn.c */
 extern int confirm(char *);
 extern int askyn(char *);