MIN: In the global section of module bufr, we now check whether the BUFR software is operational.
MIN: In the global section of module bufr, we now check whether the BUFR software is operational.

If it turns out that the BUFR software (mainly decbufr) is not operational on
that system, module bufr will raise an ImportError. In that case, util.import_optional
will raise an exception.

This change was made to allow for optional import of the BUFR module.

heistermann/wradlib,heistermann/wradlib,wradlib/wradlib,wradlib/wradlib,kmuehlbauer/wradlib,kmuehlbauer/wradlib