(Feat) Support for other data formats

[mOctave]

Currently, ESDF Manager only supports the Endless Sky data format. Other formats that may be good to support include:

• JSON
• YAML
• XML
• TOML

[mOctave]

So I've been thinking, and I might not actually go ahead with this now that I'm supporting multiple languages, because it would be a ton of work. I probably will try to find a way to make it compatible with other libraries that do let you work with multiple file formats instead.