Add option --config-location

A configfile can now be passed to youtube_dl.

undo changes

Raise parser error if file not found, change to user_conf

change metavar hand helptext for --configfile

Fix help for --configfile

Update help for --configfile

Numbering placeholder in configfile error msg

minor fix

Change option --configfile top --config-file

Fix -config-file error

youtube_dl/__init__.py

@@ -405,6 +405,7 @@ def _real_main(argv=None):
         'postprocessor_args': postprocessor_args,
         'cn_verification_proxy': opts.cn_verification_proxy,
         'geo_verification_proxy': opts.geo_verification_proxy,
+        'configfile': opts.configfile,
 
     }