Normalize the URL query
Applies Syntax-based normalization to the URL query.
Percent-encoding triplets are normalized to uppercase letters. Percent-encoded octets that correspond to unreserved characters are decoded.
assert( url( "http://www.example.com?a=%62" ).normalize_query().buffer() == "http://www.example.com?a=b" );
Strong guarantee. Calls to allocate may throw.
*this