Function plot_logs

Function to plot specific fields from training log(s). Plots both training and test results. :: Inputs - logs = list containing Path objects, each pointing to individual dir with a log file - fields = which results to plot from each

(logs,
              fields=('class_error', 'loss_bbox_unscaled', 'mAP'),
              ewm_col=0, log_name='log.txt')