URL normalization for Python

 URI Normalization function:
 .
  * Take care of IDN domains.
  * Always provide the URI scheme in lowercase characters.
  * Always provide the host, if any, in lowercase characters.
  * Only perform percent-encoding where it is essential.
  * Always use uppercase A-through-F characters when percent-encoding.
  * Prevent dot-segments appearing in non-relative URI paths.
  * For schemes that define a default authority, use an empty authority if the
    default is desired.
  * For schemes that define an empty path to be equivalent to a path of "/", use
    "/".
  * For schemes that define a port, use an empty port if the default is desired
  * All portions of the URI must be utf-8 encoded NFC from Unicode strings