Updates

Fixes the way epochs are numbered. This should ensure that all epoch counts are now consistent with each other regardless of training type.
Fixes an issue where training with iterations and gradient accumulation resulted in half iterations being run after training should've stopped.
Removes F1, recall, and precision metrics. The implementations were not generic enough to be shipped with Helios.
Refactors the MAE implementation to make it more generic in terms of the types of tensors it accepts.
Adds a numpy version of MAE.

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