render-uri uri &optional stream encode userinfo => result-string
nil.t (default), or nil:password or any Lisp object specifying what userinfo 
 should be appended to the result;nil.A string representation of uri.
This function converts uri object to result-string
and if stream in not null, output the result-string there
with the Common Lisp function write-string.
encode controls whether result-string contains percent-encoded characters and what external format should be used to encode the components of uri. It can be one of the following:
tniluserinfo specifies what authority part is output into the result string.
This function actually implements the print-object method on uri structures.