Quadtastic 0.6: Export to JSON and XML

With this update, quads can not only be saved as a Lua table, you can now also export them to JSON or XML. You can also write your own exporter if you need more flexibility.

Starting with this update, the path to the sprite sheet that is saved in the quad file is stored as a relative path. This should make it much easier to use the same quad file on different computers.

If you encounter any bugs, or have any suggestions, you can open an issue on GitHub, or post in this thread.

Full changelog:

• Add custom exporters. Custom exporters can be used to export quad definitions to formats other than the default quad file used by Quadtastic. There are default exporters for JSON and XML, but you can also write your own exporter, or use an exporter from the community. Documentation for writing exporters is available in the wiki on GitHub.
• When Turbo-Workflow is enabled, not only will the quad file be saved whenever quads change, but now the last export will be repeated, too.
• Use ctrl+e or cmd+e to repeat the previous export
• The reference to the image is now stored as a relative path in the quad file, so that quad files can be loaded on different computers without hassle
• Double-click a quad or group in the quad list to rename it
• On Windows and Linux, scroll horizontally when shift is pressed
• Fix slow scrolling on Linux and Windows
• Capture output in a log file `log.txt`. This file can be found in:
  • %appdata%\Quadtastic\ on Windows,
  • ~/Library/Application\ Support/Quadtastic/ on macOS,
  • ~/.local/share/love/ on Linux
• Fix a bug where changing directories in the file browser would not reset the file list to the beginning