Revert "[YoutubeDL] Sanitize outtmpl as it may contain forbidden characters"

This reverts commit 7dcad95d4f.

The output template is most definitly allowed to contain forbidden characters; otherwise -o /foo/bar/vid.mp4 wouldn't work.

youtube_dl/YoutubeDL.py

@@ -553,20 +553,16 @@ class YoutubeDL(object):
                 elif template_dict.get('width'):
                     template_dict['resolution'] = '?x%d' % template_dict['width']
 
-            restrict_filenames = self.params.get('restrictfilenames')
-
             sanitize = lambda k, v: sanitize_filename(
                 compat_str(v),
-                restricted=restrict_filenames,
+                restricted=self>.params.get('restrictfilenames'),
                 is_id=(k == 'id'))
             template_dict = dict((k, sanitize(k, v))
                                  for k, v in template_dict.items()
                                  if v is not None)
             template_dict = collections.defaultdict(lambda: 'NA', template_dict)
 
-            outtmpl = sanitize_filename(
-                self.params.get('outtmpl', DEFAULT_OUTTMPL),
-                restricted=restrict_filenames)
+            outtmpl = self.params.get('outtmpl', DEFAULT_OUTTMPL)
             tmpl = compat_expanduser(outtmpl)
             filename = tmpl % template_dict
             # Temporary fix for #4787