implement ODIM BUFR readers

[jfigui]

At the last OPERA ET meeting it emerged that there is a real interest for xradar to have and ODIM BUFR reader, in particular to read the French radar data. I am fully aware that that is not an easy task but considering that there are plans to open the OPERA data archive and that, particularly at the early stages of the OPERA program, many files are in BUFR format this would be very welcomed by the European radar community.