Fix RHold display for delay repeats.

This involved passing the EffectValue resulting from the resolution of
an VALUE_TYPE_EXTRA to map_xml_value() and some more careful range
checking.

Also, the delay repeats effect needed an xml_label for the special
'repeat forever' value 100, which maps to the string RHold.

gdigi.c

@@ -142,7 +142,7 @@ format_value (XmlSettings *xml, guint value)
     switch (vtype) {
     case VALUE_TYPE_LABEL:
     {
-        char *textp = map_xml_value(xml, value);
+        char *textp = map_xml_value(xml, values, value);
         if (!textp) {
             g_warning("Unable to map %s value %d for id %d position %d",
                       xml->label, value, xml->id, xml->position);