* add --skip-msgid-dups / -u option to mu find, document it

mu/mu-cmd-find.c

@@ -127,6 +127,8 @@ run_query (MuQuery *xapian, const gchar *query, MuConfig *opts,  GError **err)
 		qflags |= MU_QUERY_FLAG_THREADS;
 	if (opts->reverse)
 		qflags |= MU_QUERY_FLAG_DESCENDING;
+	if (opts->no_msgid_dups)
+		qflags |= MU_QUERY_FLAG_SKIP_MSGID_DUPS;
 
 	iter = mu_query_run (xapian, query, sortid, -1, qflags, err);
 	return iter;

mu/mu-config.c

@@ -213,6 +213,10 @@ config_options_group_find (void)
 		 "use a bookmarked query", "<bookmark>"},
 		{"reverse", 'z', 0, G_OPTION_ARG_NONE, &MU_CONFIG.reverse,
 		 "sort in reverse (descending) order (z -> a)", NULL},
+		{"no-msgid-dups", 'u', 0, G_OPTION_ARG_NONE,
+		 &MU_CONFIG.no_msgid_dups,
+		 "only show the first of multiple messages with the same "
+		 "message-id (false)", NULL},
 		{"linksdir", 0, 0, G_OPTION_ARG_STRING, &MU_CONFIG.linksdir,
 		 "output as symbolic links to a target maildir", "<dir>"},
 		{"clearlinks", 0, 0, G_OPTION_ARG_NONE, &MU_CONFIG.clearlinks,

mu/mu-config.h

@@ -139,6 +139,10 @@ struct _MuConfig {
 	gchar		*exec;		/* command to execute on the
 					 * files for the matched
 					 * messages */
+	gboolean        no_msgid_dups;  /* if there are multiple
+					 * messages with the same
+					 * msgid, show only the first
+					 * one */
 	/* for find and cind */
 	time_t            after;          /* only show messages or
 					   * adresses last seen after