fix some errors

[takeyamayuki]

The following errors have been corrected.

• Function 'nanmean' (input argument of type 'single') is undefined. #4

• Cannot import classes in models directory when running python evaluate/evaluate.py to evaluate it.

  Traceback (most recent call last):
    File "F:\EventPointPose\evaluate\evaluate.py", line 7, in <module>
      from eval_run_tools import init_point_model
    File "F:\EventPointPose\evaluate\eval_run_tools.py", line 15, in <module>
      from eval_args_tools import point_args_init, point_model_init
    File "F:\EventPointPose\evaluate\eval_args_tools.py", line 10, in <module>        
      from models import Pose_PointNet, Pose_DGCNN, Pose_PointTransformer
  ModuleNotFoundError: No module named 'models'