Kwcoco

Added:
* Add `remember_parent` option to CocoDataset.union
* Add `CocoDataset.coerce_multiple` and `load_multiple` loader with parallel processing.
* Add parallel IO to `kwcoco union`
* Add util parallel and eval

Fixed:
* Issue in detection metrics when classes was not specified. Now uses the true
detections to infer them if possible.
* Detection metric assign workers was never used
* Subsets of metrics now work when TN is not available.

Changed
* CLI backend changed to use scriptconfig ModalCLI

Changed
* CocoImage and CocoAsset use the new AliasDictProxy interface to smoothly
transition between name conventions.
* The "assets" key is now an alias of "auxiliary" for CocoImage and we will switch to "assets" as the primary in the future.
* Toydata now generates RGB bands independently
* Change `__unstructured__` to `_unstructured` for sqlalchemy 2.x compat

Added
* demo data now has the ability to render on top of a background image.

Fixed
* Fixed sqlalchemy 2.x compatibility
* The track index now works properly with SQL variants and returns ordreing

Changed
* Toydata now has better polygon generation for small image sizes, but is still
not perfect.
* Changed the internal name used in compressed zip files.

Fixed
Bug in `CocoImage.add_asset` where json serialization was broken

Changed
* In `metrics.drawing`, make threshold colors more consistent
* Added `category_names` property to `Annots1d` object.
* Deprecate `CocoImage.add_auxiliary_item` in favor of `CocoImage.add_asset`

Added
* Added `annots` property to CocoImage
* Added `add_annotation` to `CocoImage`
* Added `autofix` option `kwcoco reroot`

Fixed
* Better asset space support
* Querying `annots` by track-id now return them in a sorted order.

Added
* Can now ask for the resolution of an asset in CocoImage.


Changed
* Renamed `CocoImage.delay` to `CocoImage.imdelay`. The old name will be available as an alias, but will eventually be deprecated.
* Import time is now much faster.
* default `check_aux` to True in `CocoDataset.missing_images`

Added
* Experimental support for reading / writing kwcoco files to / from zipfiles.

Changed
* Improved splitting in kwcoco split CLI. Better handling for video datasets. Category balance is now optional.

Fixed
* Bug where specifying resolution to `delay` would not work if the channels did not exist.