KMLSuperOverlay: recognize an alternate structure for raster KMZ file made of a single doc.kml and tiles whose name pattern is kml_image_L{level}_{j}_{i}.{png|jpg}

git-svn-id: https://svn.osgeo.org/gdal/trunk@27042 f0d54148-0727-0410-94bb-9a71ac55c965