[util] Move compatibility functions out of util

utils is large enough without these compatibility functions.

Everything that is present in newer versions of Python (i.e. with dev Python it's just an import) goes into compat.py .
Everything else (i.e. youtube-dl-specific helpers) goes into utils.py .

youtube_dl/extractor/addanime.py

@@ -3,12 +3,13 @@ from __future__ import unicode_literals
 import re
 
 from .common import InfoExtractor
-from ..utils import (
+from ..compat import (
     compat_HTTPError,
     compat_str,
     compat_urllib_parse,
     compat_urllib_parse_urlparse,
-
+)
+from ..utils import (
     ExtractorError,
 )
 

youtube_dl/extractor/cloudy.py

@@ -4,14 +4,16 @@ from __future__ import unicode_literals
 import re
 
 from .common import InfoExtractor
-from ..utils import (
-    ExtractorError,
+from ..compat import (
     compat_parse_qs,
     compat_urllib_parse,
-    remove_end,
-    HEADRequest,
     compat_HTTPError,
 )
+from ..utils import (
+    ExtractorError,
+    HEADRequest,
+    remove_end,
+)
 
 
 class CloudyIE(InfoExtractor):

youtube_dl/extractor/common.py

@@ -12,13 +12,14 @@ import sys
 import time
 import xml.etree.ElementTree
 
-from ..utils import (
+from ..compat import (
     compat_http_client,
     compat_urllib_error,
     compat_urllib_parse_urlparse,
     compat_urlparse,
     compat_str,
-
+)
+from ..utils import (
     clean_html,
     compiled_regex_type,
     ExtractorError,

youtube_dl/extractor/crunchyroll.py

@@ -17,7 +17,6 @@ from ..utils import (
     bytes_to_intlist,
     intlist_to_bytes,
     unified_strdate,
-    clean_html,
     urlencode_postdata,
 )
 from ..aes import (

youtube_dl/extractor/dropbox.py

@@ -5,7 +5,8 @@ import os.path
 import re
 
 from .common import InfoExtractor
-from ..utils import compat_urllib_parse_unquote, url_basename
+from ..compat import compat_urllib_parse_unquote
+from ..utils import url_basename
 
 
 class DropboxIE(InfoExtractor):

youtube_dl/extractor/facebook.py

@@ -5,12 +5,14 @@ import re
 import socket
 
 from .common import InfoExtractor
-from ..utils import (
+from ..compat import (
     compat_http_client,
     compat_str,
     compat_urllib_error,
     compat_urllib_parse,
     compat_urllib_request,
+)
+from ..utils import (
     urlencode_postdata,
     ExtractorError,
     limit_length,

youtube_dl/extractor/generic.py

@@ -7,11 +7,12 @@ import re
 
 from .common import InfoExtractor
 from .youtube import YoutubeIE
-from ..utils import (
+from ..compat import (
     compat_urllib_parse,
     compat_urlparse,
     compat_xml_parse_error,
-
+)
+from ..utils import (
     determine_ext,
     ExtractorError,
     float_or_none,

youtube_dl/extractor/globo.py

@@ -5,13 +5,15 @@ import random
 import math
 
 from .common import InfoExtractor
-from ..utils import (
-    ExtractorError,
-    float_or_none,
+from ..compat import (
     compat_str,
     compat_chr,
     compat_ord,
 )
+from ..utils import (
+    ExtractorError,
+    float_or_none,
+)
 
 
 class GloboIE(InfoExtractor):

youtube_dl/extractor/laola1tv.py

@@ -4,6 +4,7 @@ import random
 import re
 
 from .common import InfoExtractor
+from ..utils import ExtractorError
 
 
 class Laola1TvIE(InfoExtractor):

youtube_dl/extractor/myvideo.py

@@ -7,11 +7,12 @@ import re
 import json
 
 from .common import InfoExtractor
-from ..utils import (
+from ..compat import (
     compat_ord,
     compat_urllib_parse,
     compat_urllib_request,
-
+)
+from ..utils import (
     ExtractorError,
 )
 

youtube_dl/extractor/ro220.py

@@ -1,7 +1,7 @@
 from __future__ import unicode_literals
 
 from .common import InfoExtractor
-from ..utils import compat_urllib_parse_unquote
+from ..compat import compat_urllib_parse_unquote
 
 
 class Ro220IE(InfoExtractor):

youtube_dl/extractor/vimeo.py

@@ -7,11 +7,13 @@ import itertools
 
 from .common import InfoExtractor
 from .subtitles import SubtitlesInfoExtractor
-from ..utils import (
+from ..compat import (
     compat_HTTPError,
     compat_urllib_parse,
     compat_urllib_request,
     compat_urlparse,
+)
+from ..utils import (
     ExtractorError,
     InAdvancePagedList,
     int_or_none,