fix netcdf driver geotransform detection (#5118 and #5114)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26108 f0d54148-0727-0410-94bb-9a71ac55c965
fix netcdf driver irregular grids management (#5118 and #4513)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26109 f0d54148-0727-0410-94bb-9a71ac55c965