Add print(results) override for PyTorch Hub results

[glenn-jocher]

Usage example:

import torch

# Model
model = torch.hub.load('ultralytics/yolov5', 'yolov5s')  # or yolov5m, yolov5l, yolov5x, custom

# Images
img = 'https://ultralytics.com/images/zidane.jpg'  # or file, Path, PIL, OpenCV, numpy, list

# Inference
results = model(img)

# Results
results.print()
print(results)  # <---- NEW 

# image 1/1: 720x1280 2 persons, 2 ties
# Speed: 299.5ms pre-process, 319.2ms inference, 12.9ms NMS per image at shape (1, 3, 384, 640)

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improved usability of model results in Ultralytics YOLOv5 with new string representation.

📊 Key Changes

• 🧩 Added an override of the __str__ method to the Results class.
• 🖨️ Modified the __len__ method comment for clarity.

🎯 Purpose & Impact

• 👁️‍🗨️ Enhances the user's visibility of results by automatically printing when using the print() function on a Results object.
• 🌐 Provides a more Pythonic usage experience, as users expect print(object) to display useful information.
• 🆒 Potentially improves debugging and logging with minimal changes to existing codebases.