r.in.gdal Improvements Needed

[warmerdam]

Andrey,

Could you please make the following improvements to r.in.gdal as time permits.
No hurry.

1) If a raster has zero raster bands, error out with a brief explanation 
   instead of trying to fetch band zero and crashing. 

2) If a file has subdataset metadata, provide an option to list the subdatasets.
Minimally provide the datasetnames that would be needed to use to import them.
Ideally offer a commandline option to import all sub-datasets. 

Thanks,

[rouault]

Transfered as a GRASS ticket :  http://trac.osgeo.org/grass/ticket/798