geke-mir

Segmentation annotations default flow modifications

1

## What changes are proposed in this pull request? Require users to specify a `mask_targets` argument for new segmentations annotations, otherwise fall back onto the dataset's defaults specified in `dataset.mask_targets`...

[BUG] Default mask targets are not used when creating new segmentation annotation tasks

2

### Describe the problem The documentation states that datasets can have `dataset.default_mask_targets` or `dataset.mask_targets` here: https://docs.voxel51.com/user_guide/using_datasets.html#storing-mask-targets When creating a new segmentation task with FiftyOne without specifying `mask_targets`, classes 0-255 appear...