add configuration options (#164)

e.g. python tools/main.py --c configs/stylegan_v2_256_ffhq.yaml -o total_iters=1 log_config.visiual_interval=1

ppgan/utils/options.py

@@ -45,10 +45,10 @@ def parse_args():
                         default=False,
                         help='skip validation during training')
     # config options
-    parser.add_argument('opts',
-                        help='See config for all options',
-                        default=None,
-                        nargs=argparse.REMAINDER)
+    parser.add_argument("-o", 
+                        "--opt", 
+                        nargs='+', 
+                        help="set configuration options")
 
     #for inference
     parser.add_argument("--source_path",

tools/main.py

@@ -51,6 +51,6 @@ def main(args, cfg):
 
 if __name__ == '__main__':
     args = parse_args()
-    cfg = get_config(args.config_file)
+    cfg = get_config(args.config_file, args.opt)
 
     main(args, cfg)