General refactoring and improvements (#373)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/yolo/v8/segment/train.py

@@ -143,7 +143,7 @@ class SegLoss(Loss):
 
 @hydra.main(version_base=None, config_path=str(DEFAULT_CONFIG.parent), config_name=DEFAULT_CONFIG.name)
 def train(cfg):
-    cfg.model = cfg.model or "yolov8n-seg.yaml"
+    cfg.model = cfg.model or "yolov8n-seg.pt"
     cfg.data = cfg.data or "coco128-seg.yaml"  # or yolo.ClassificationDataset("mnist")
     cfg.device = cfg.device if cfg.device is not None else ''
     # trainer = SegmentationTrainer(cfg)
@@ -154,11 +154,4 @@ def train(cfg):
 
 
 if __name__ == "__main__":
-    """
-    CLI usage:
-    python ultralytics/yolo/v8/segment/train.py model=yolov8n-seg.yaml data=coco128-segments epochs=100 imgsz=640
-
-    TODO:
-    Direct cli support, i.e, yolov8 classify_train args.epochs 10
-    """
     train()