* Update train.py

As see in #6463, modification on train in evolve process to allow custom save directory.

* fix val

* PEP8

whitespace around operator

* Cleanup

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Fix `plot_labels()` colored histogram bug

* Cleanup

* Improved AutoBatch DDP error message

* Cleanup

* Move trainloader functions to class methods

* results = ThreadPool(NUM_THREADS).imap(self.load_image, range(n))

* Cleanup

* F541

* F821

* F841

* E741

* E302

* E722

* Apply suggestions from code review

* Update general.py

* Update datasets.py

* Update export.py

* Update plots.py

* Update plots.py

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Load checkpoint on CPU instead of on GPU

* refactor: simplify code

* Cleanup

* Update train.py

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

Update `lrf: 0.1`, tested on YOLOv5x6 to 55.0 mAP@0.5:0.95, slightly higher than current.

* log best.pt metrics at train end

* update

* Update __init__.py

* flush callbacks when using evolve

* remember batch size on resuming

* Update train.py

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

Suppresses warnings when calling export.run() directly, not just CLI python export.py.

Also adds Requirements examples for CPU and GPU backends

* Suppress torch.jit.TracerWarning

TracerWarnings can be safely ignored.

* Cleanup

* Improved `export.py` usage examples

* Cleanup

* Social media icons update

* fix URL

* Update README.md

* Fix2 select_device() for Multi-GPU

* Cleanup

* Cleanup

* Simplify error message

* Improve assert

* Update torch_utils.py

* Verbose updates

* Verbose updates

* Workflow updates

* quotes fix

* best to weights fix

* import tflite_runtime if tensorflow not installed

* rename tflite to tfli

* Attempt tflite_runtime for all TFLite workflows

Also rename tfli to tfl

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Gave a more explicit name to the logger

* Cleanup

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Update `greetings.yaml` email address

* Update greetings.yml

* Add detect.py GIF video inference

* Cleanup

* New flag 'stop_training' in util.callbacks.Callbacks class to prematurely stop training from callback handler

* Removed most of the new  checks, leaving only the one after calling 'on_train_batch_end'

* Cleanup

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

21.12 generates dockerhub errors so rolling back to 21.10 with latest pytorch install. Not sure if this torch install will work on non-GPU dockerhub autobuild so this is an experiment.

* log best.pt metrics at train end

* update

* Update __init__.py

* flush callbacks when using evolve

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

New environment variable `VERBOSE`

* `export.py` return exported files/dirs

* Path to str