Instagrain prototype - case v3; Software and Model v0.2

This is a minor update from the first release.

Improvements include:

• new case designs (v3 - smaller, no coral, fewer cuts)
• notebook for new model, based on new training samples
• new .tflite model
• software enhancements (load a previous session)
• Zenodo DOI for release.

This should be considered an Alpha level release - more testing is needed for hardware, software, and the ML model.