v1.6.0: Improve docstrings, add multi-version support to epic_kitchens.meta

Features

• Add epic_kitchens.meta package containing helpers for downloading and reading label class definitions, and training and test set annotations.
• Add epic_kitchens.data.visualisation package containing tools that allow you to view arbitrary action segments RGB or Flow contained in a EpicVideoDataset using moviepy. This is useful when sifting through results per instance.