Fix call os lyx2lyx as a module.

If we call parser.parse_args(), thus with no arguments, the parser uses
sys.argv (because that is the default). We should pass argv since that was
the purpose of handling argv in the main function.

lib/scripts/layout2layout.py

@@ -1179,7 +1179,7 @@ def main(argv):
     parser.add_argument("output_file", nargs='?', type=cmd_arg, default=None,
                         help="output file (default stdout)")
 
-    options = parser.parse_args()
+    options = parser.parse_args(argv)
 
     # Open files
     if options.input_file: