Feature request: Export as JSON file

[paolocamerin]

I love the tool and I am using it quite often also for work purposes.

I think the possibility to export to JSON file would be quite useful for certain use case scenarios.
For example I would like to take the out put and import it into a JS project and use it there accessing the data rather than using the sprite itself.
Maybe a bit of edge case, I am not sure.
But since I see there is a possibility to export to C, and the file structure looks similar to what a JSON file would look like, I think having an explicit option to export to JSON would be great!