net/url-string: change parsing of "file:" URLs for Windows
net/url-string: change parsing of "file:" URLs for Windows

History of the parsing of "file:" URLs for Windows:

 * In response to PR 8060 (April 2006): special handling added to
   support ill-formed URLs that were (are?) commonly used for
   filesystem paths.

 * Follow-up to PR 8060 (April 2008): added `path->url` and
   `url->path`.

 * In response to #1086 (October 2015, the commit): changed
   Windows-specific handling to be more constrained and added support
   for the proper encoding of UNC paths --- where "proper" means
   "according to a blog post from late 2006", which appears to be as
   close as we get to documentation of the URL encoding for Windows
   paths.

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket