Changes:
* Moved to Python 3 with standard Python package (Also published to PyPI)
* Added plugin support
* Added option for custom breaks
* Added optional break images
* Added lock screen support after long breaks
* Prevent disabling Safe Eyes after notification in strict break mode
* Use system language by default if available
* Update configuration without losing the settings
* Append to the `safeeyes.log` file instead of overwriting (Max size is 5MB)
* Fix disable menu issue in Elementary OS and Manjaroo KDE
* Fix stretched switch buttons in some desktop environments
* Increased the break screen font size
* Translatable About dialog
* Minor bug fixes