Implementation of python escaping.

This implementation encodes non-printable characters (0x00-0x1f, 0x7f-0xff) to hex-value characters ('\xhh') while leaving printable characters as such:

 > encode [0, 10, 13, 110]
 "\\x00\\x0A\\x0Dn"
 > putStrLn $ encode [0, 10, 13, 110]
 \x00\x0A\x0Dn

It also properly handles escaping of a few characters that require it:

 > encode [34, 39, 92]
 "\\\"\\'\\\\"
 putStrLn $ encode [34, 39, 92]
 \"\'\\

Further documentation and information can be found at http://www.haskell.org/haskellwiki/Library/Data_encoding.