image2pixel v2.1.5

### v2.1.5
- Learning data can now be exported and imported as files, and organized into multiple named datasets (like palettes) — create, activate, and manage them with the new card-based UI.
- Clearing learned data is now tucked into a danger zone with double confirmation.
- Steam Cloud now syncs all learning datasets across devices.
- Updated version to 2.1.5.