wdbc: Clean up some code, remove GtDBCFile and SimpleDBCFile since we don't need them anymore. Use Field.size rather than trying to guess the size for each column.
wdbc: Clean up some code, remove GtDBCFile and SimpleDBCFile since we don't need them anymore. Use Field.size rather than trying to guess the size for each column.

jleclanche/pywow,jleclanche/pywow,jleclanche/pywow,jleclanche/pywow,jleclanche/pywow,jleclanche/pywow