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· Fix some outdated tests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/downloader/hls.py

@@ -6,9 +6,11 @@ import subprocess
 
 from ..postprocessor.ffmpeg import FFmpegPostProcessor
 from .common import FileDownloader
-from ..utils import (
+from ..compat import (
     compat_urlparse,
     compat_urllib_request,
+)
+from ..utils import (
     check_executable,
     encodeFilename,
 )