Add @threaded decorator

[glenn-jocher]

🛠️ PR Summary

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🌟 Summary

Enhancements to threading and logging in the YOLOv5 codebase.

📊 Key Changes

• Added a threaded decorator to manage the creation and start of threads in a more Pythonic way.
• Removed direct usage of Thread from threading and replaced with the @threaded decorator.
• Streamlined dictionary creation with direct dict(zip(...)) usage for better readability.
• Cleaned up and refactored logging callbacks to be more concise.
• Amended a check in plot_images for determining if a label fits outside the box.
• Updated variable naming for color palettes to improve code clarity.
• General code cleanups like removing unused imports and simplifying function calls.

🎯 Purpose & Impact

• The introduction of the @threaded decorator simplifies multi-threading, reducing code verbosity, and potentially lowering the risk of errors associated with thread management.
• Changes to the logging process and dictionary creations make the code easier to read, understand, and maintain, which benefits developers working on the codebase.
• Tweaks to the plotting function affect the presentation of visual results and improve decision-making for positioning box labels.
• Overall impact includes cleaner, more maintainable code with potentially fewer bugs, leading to an improved experience for contributors and end-users of YOLOv5. 🧑‍💻🛠️