Rasdaman: caching of tiles for datasets with more than one band; connections are now kept for a whole session; fixing connection-string regex; fixing possible memory leaks (patch by Fabian Schindler, #5298)

git-svn-id: https://svn.osgeo.org/gdal/trunk@26638 f0d54148-0727-0410-94bb-9a71ac55c965