Implement byte pack/unpack code for buffers of unsigned types

Direct buffers cannot be used with unsigned types without byte
packing/unpacking code. If a native unsigned type is copied to a direct
buffer, the high byte will not be set correctly.

This could be worked around in some cases by using the access method for
the next-larger type and relying on the internal HDF conversion code.
However, it should be addressed so that CharBuffer can be used to store UTF
data. For completeness, the other unsigned types should be addressed as well. 

Methods using the packing code should be documented, because there will
probably be a performance hit.

Original issue reported on code.google.com by solomon....@gmail.com on 12 Dec 2008 at 6:43

ekjstm / permafrost

Implement byte pack/unpack code for buffers of unsigned types #11