Fix imports and general cleanup

· Import from compat what comes from compat. Yes, some names are available in utils too, but that's an implementation detail.
· Use _match_id consistently whenever possible
· Fix some outdated tests
· Use consistent valid URL (always match the whole protocol, no ^ at start required)
· Use modern test definitions

youtube_dl/extractor/aol.py

@@ -68,4 +68,3 @@ class AolIE(InfoExtractor):
             'title': title,
             'entries': entries,
         }
-