update os.sep

Master

Handle multiple datasets

Move hyp and opt yaml save to top of train()

Fixes bug where scaled values were saved in hyp.yaml, which would cause continuity issues with --resume

Log command line options, hyperparameters, and weights per run in `runs/`

[bug fix] potential problem if img fed to model is in rectangular shape

Update CoreML model conversion to do pixel scaling as well

Updated coreml conversion to do pixel scaling between 0.0 and 1.0

Remove from advanced_logging branch before merge.