Fastai

New Features

- added support for tb projector word embeddings ([2853](https://github.com/fastai/fastai/pull/2853)), thanks to [floleuerer](https://github.com/floleuerer)
- Added ability to have variable length draw ([2845](https://github.com/fastai/fastai/pull/2845)), thanks to [marii-moe](https://github.com/marii-moe)
- add pip upgrade cell to all notebooks, to ensure colab has current fastai version ([2843](https://github.com/fastai/fastai/issues/2843))

Bugs Squashed

- fix TabularDataLoaders inference of cont_names to keep y_names separate ([2859](https://github.com/fastai/fastai/pull/2859)), thanks to [sutt](https://github.com/sutt)

Breaking Changes

- loss functions were moved to `loss.py` ([2843](https://github.com/fastai/fastai/pull/2810))

New Features

- new callback event: `after_create` ([2842](https://github.com/fastai/fastai/issues/2842))
- This event runs after a `Learner` is constructed. It's useful for initial setup which isn't needed for every `fit`, but just once for each `Learner` (such as setting initial defaults).

- Modified XResNet to support Conv1d / Conv3d ([2744](https://github.com/fastai/fastai/pull/2744)), thanks to [floleuerer](https://github.com/floleuerer)
- Supports different input dimensions, kernel sizes and stride (added parameters ndim, ks, stride). Tested with fastai_audio and fastai time series with promising results.

Bugs Squashed

- `img_size` attribute for `TensorPoint` is not updated properly ([2799](https://github.com/fastai/fastai/pull/2799)), thanks to [IRailean](https://github.com/IRailean)

Bugs Squashed

- Undo breaking num_workers fix ([2804](https://github.com/fastai/fastai/pull/2804))
- Some users found the recent addition of `num_workers` to inference
functions was causing problems, particularly on Windows. This PR
reverts that change, until we find a more reliable way to handle
`num_workers` for inference.
- learn.tta() fails on a learner imported with load_learner() ([2764](https://github.com/fastai/fastai/issues/2764))
- learn.summary() crashes out on 2nd transfer learning ([2735](https://github.com/fastai/fastai/issues/2735))

Bugs Squashed

- Undo breaking `num_workers` fix ([2804](https://github.com/fastai/fastai/pull/2804))

Bugs Squashed

- Fix `cont_cat_split` for multi-label classification ([2759](https://github.com/fastai/fastai/issues/2759))
- fastbook error: "index 3 is out of bounds for dimension 0 with size 3" ([2792](https://github.com/fastai/fastai/issues/2792))