Lpd

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* Bug fix when saving full trainer that has tensorboard callback
* Added LossOptimizerHandlerAccumulateSamples
* Added LossOptimizerHandlerAccumulateBatches
* Added is_file_exists method to file_utils

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* Added new callback - TensorboardImage
* Added example for TensorboardImage
* Added torchvision to requirements-dev.txt
* In Trainer - metric_name_to_func (dict) was changed to metrics (list)
* Trainer now holds _last_data property - a class InputOutputLabel that holds (inputs, outputs, labels)
* New method in file_utils ensure_folder_created

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* Added lpd-nodeps package in case you need to handle your own dependencies

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* Improved handling of MetricConfusionMatrixBase with custom metrics

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* CallbackMonitor patience argument now optional for cleaner code
* Better handling for binary get_stats in confusion matrix based metric

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* Added MetricConfusionMatrixBase for adding custom confusion matrix based metrics
* Added ConfusionMatrixBasedMetric Enum to get specific metrics such as tp,fp,fn,tn,precision,sensitivity,specificity,recall,ppv,npv,accuracy,f1score
* Added confusion matrix common metrics (TruePositives, TrueNegatives, FalsePositives, FalseNegatives)
* Added MetricMethod enum to pass to MetricBase, now you can define whether your metric is based on MEAN, SUM or LAST of all batches
* StatsPrint callback now support "print_confusion_matrix" and "print_confusion_matrix_normalized" arguments in case MetricConfusionMatrixBase metric is found
* Added confusion matrix tests and example
* Some custom layers renames (breaking changes in this part)