net/url: sub delimiters are percent encoded unnecessarily.

[DanielMorsing]

"!$&'()*+,;=" is the sub-delims class in RFC 3986. As such, they're
allowed in every part of a URL apart from the scheme, but the Go URI formatter escapes
"()'!" anyway.

Example:
http://play.golang.org/p/JrYygt6C5q

[bradfitz]

Comment 1:

Pretty sure this is a duplicate. Let me know if not.

Status changed to Duplicate.

Merged into issue #5684.