Remove Remember last downloaded files preference

The preference was never actually implemented.

midori/midori-preferences.c

@@ -592,6 +592,4 @@ midori_preferences_set_settings (MidoriPreferences* preferences,
     SPANNED_ADD (button);
     label = gtk_label_new (_("days"));
     SPANNED_ADD (label);
-    button = katze_property_proxy (settings, "remember-last-downloaded-files", NULL);
-    INDENTED_ADD (button);
 }

midori/midori-websettings.c

@@ -988,6 +988,13 @@ midori_web_settings_class_init (MidoriWebSettingsClass* class)
                                      0, G_MAXINT, 30,
                                      flags));
 
+    /**
+     * MidoriWebSettings:remember-last-downloaded-files:
+     *
+     * Whether the last downloaded files are saved.
+     *
+     * Deprecated: 0.2.9
+     **/
     g_object_class_install_property (gobject_class,
                                      PROP_REMEMBER_LAST_DOWNLOADED_FILES,
                                      g_param_spec_boolean (