Normalize absolute urls with default domain name.

[luckydonald]

It should be possible to specify a default_scheme similar to the already possible default_scheme.

E.g.

>>> url_normalize('/foo.png', default_scheme='https', default_domain='example.com')
'https://example.com/foo.png'

Currently that is not possible:

>>> url_normalize('/foo.png', default_scheme='https')
'/foo.png'

[luckydonald]

This could be done with the following

def provide_url_scheme(url, default_scheme=DEFAULT_SCHEME, default_host=None):
    has_scheme = ":" in url[:7]
    is_universal_scheme = url.startswith("//")
    is_stdout = url == "-"
    is_file_path = is_stdout or (url.startswith("/") and not is_universal_scheme)
    if default_host and is_file_path and not is_stdout:
        if is_universal_scheme:
            return default_scheme + ":" + default_host + url
        return default_scheme + "://" + default_host + url
    if not url or has_scheme or is_file_path:
        return url
    if is_universal_scheme:
        return default_scheme + ":" + url
    return default_scheme + "://" + url

All that has to be added to url_normalize(…) is:

 def url_normalize(
-    url, charset=DEFAULT_CHARSET, default_scheme=DEFAULT_SCHEME, sort_query_params=True
+    url, charset=DEFAULT_CHARSET, default_scheme=DEFAULT_SCHEME, default_host=None, sort_query_params=True
 ):
     if not url:
         return url
-    url = provide_url_scheme(url, default_scheme)
+    url = provide_url_scheme(url, default_scheme, default_host)

Which could look like this in the end:

>>> url_normalize('/blahbla/whatever.png', default_host='example.com')
'https://example.com/blahbla/whatever.png'