Plenopticam

The following features have been added to this release:

- Jupyter lab notebooks launching on Binder or Colab accessible via badges in ReadMe (or [here](https://mybinder.org/v2/gh/hahnec/plenopticam/develop?urlpath=lab))
- unit tests for CLI, GUI and error handling which increase coverage by 10%
- minor refactoring of API to facilitate the above changes

Release v0.5.2 features a first jupyter notebook example and minor refactoring to facilitate this.

- fix for load/save in settings window
- improved gamma handling for images other than Lytro's
- enhanced runtime stability through bug fixes in calibration pipeline

This release contains:
- major enhancements on the reliability of a robust and generic calibration
- extended CLI options access (e.g. grid-fit, scheimpflug)
- general bug fixes

- more reliable handling of micro image size
- fix in viewer when data not available
- fix in viewer for Linux version
- refactoring of code for better structure and readability