Sleap

- GUI for metrics on trained models
- more options when exporting clip with visual annotations

Bug fixes for issues 370 (default filename extension when saving on Linux) and 374 (anchor part issues when training from GUI).

This release is just bug fixes:

- training gui dialog: the anchor part name wasn't copied into instance cropping config
- training/model eval: if anchor part wasn't set in instance cropping config, then the eval model code failed on centered instance models
- file save gui: if using non-native save dialog, the file ext wasn't automatically added to filename and save failed if user didn't add it

- Kalman filter-based tracking
- confidence map refinement fixes
- run eval after training
- other misc changes

Automated release of 1.0.4a7 on 2020-06-25

Automated release of 1.0.4a6 on 2020-06-25