fix smaller stuff

- change filename option in example config file
- adapt default filename format for mangafox
- remove unnecessary newline

[skip ci]

gallery_dl/__init__.py

@@ -102,7 +102,6 @@ def main():
             log.debug("Version %s", __version__)
             log.debug("Python %s - %s",
                       platform.python_version(), platform.platform())
-            print(file=sys.stderr)
 
         if args.list_modules:
             for module_name in extractor.modules: