Fix decoding of single-bit fields.

This fixes, for instance, land-sea masks, like those in the GFS. The fix
came from the Richard Peter. See:

http://www.unidata.ucar.edu/support/help/MailArchives/decoders/msg00929.html
Rename enum -> en.

This silences some Java warnings.
Comment out calls to System.runFinalizersOnExit()

This is deprecated since JDK 1.2 and are only used in profiling.
Commenting out silences some Java warnings.