change sorting to lexicographic

After discussing on the mailing list, my best guess at the correct/standard
sorting order is actually "lexicographic", i.e. as strings. I have tried to
start a discussion of this and as of this moment have not yet gotten any
responses:

http://sourceforge.net/p/bitcoin/mailman/message/32092958/
improve formatting of README
remove superfluous sort function; change pubkeys to bufs
add redeemScript and address functions