o This takes on board comments by Raymond Toy, and drops optimizations
and implementation-specific cruft that isn't really needed.
o The code has been reorganized quite a bit, to better expose the
structure
o md5-checksum is renamed to md5-digest.
o Added doc-strings and comments where necessary, added documentation to
the file comment.
o Added md5sum-sequence function.
o Fixed restriction on <512MB of input, we now support unlimited amounts
of input, as required by the spec. Since this causes one possibly
bignum addition per call to update-md5-block, the user can revert
to the old behaviour by putting :md5-small-length on *features* prior
to compiling/loading the code.
o Added test suite that is contained in Appendix A.5 of RFC 1321.
using kernel:32bit-logical-* instead of the silly signed-byte acrobatics
that were previously needed to get the various logical and ash operations
optimized. Also added rudimentary file-comment.
