Addons: Hide status icon on startup until Geany has started

This avoids showing the status icon without an icon on startup and
even if it is disabled while Geany is starting.

addons/src/ao_systray.c

@@ -189,6 +189,7 @@ static void ao_systray_init(AoSystray *self)
 	const gchar *icon_name;
 
 	priv->icon = gtk_status_icon_new();
+	gtk_status_icon_set_visible(priv->icon, FALSE);
 	icon_name = gtk_window_get_icon_name(GTK_WINDOW(geany->main_widgets->window));
 	if (icon_name) /* Geany >= 1.23 */
 		gtk_status_icon_set_from_icon_name(priv->icon, icon_name);