This provides a new DESCRIBERUNTIMEMAP operation which provides the means of returning the same CREATERUNTIMEMAP structure for existing runtime maps (mapname + session id). This is needed for:
a) Fusion to be able to reload a map (eg. after a Buffer or Redline that adds new layers) without going through the LoadMap.php/LoadScaleRanges.php chain
b) Any client application that needs to re-interrogate the structure of a Runtime Map with a map name and session id.