Md5 module README

Md5 is a so-called message-digest algorithm developed by Ronald Rivest
(the 'R' in RSA).  See RFC 1321 for details.  This is a very powerful
and relatively efficient means of verifying the integrity of a block
of data, such as a downloaded application image.

This module currently provides two implementations of Md5, selectable
by #define, behind a single API.

On a BCM12500 processor running at 450MHz, it takes about 150ms to Md5
1 megabyte of data if compiled with -O0 (no optimization).  It takes
only 40ms to Md5 1 megabyte of data when compiled with -O3 (full
optimization).

