fix multiprocessing issue in windows environment (#118)

src/main.py

@@ -10,6 +10,8 @@ from trainer import Trainer
 torch.manual_seed(args.seed)
 checkpoint = utility.checkpoint(args)
 
+def main():
+    global model
     if args.data_test == 'video':
         from videotester import VideoTester
         model = model.Model(args, checkpoint)
@@ -27,3 +29,5 @@ else:
 
             checkpoint.done()
 
+if __name__ == '__main__':
+    main()