Export amod to other formats (JSON, XML)

[asmaloney]

(Suggestion from @kenwebb.)

Add translating/exporting of the amod file to other open formats such as XML and JSON. This would allow other tools to use the amod models without having to parse the amod format and validate the model.

I'm not opposed to this idea in principle. While implementing this should not be too complex, it would add a maintenance burden - any time the amod format or the internal representation changed, the exporters would need updating.

Rather than implementing something that might be useful, I think it makes sense to let the amod format mature a bit and wait for a project that would actually use this.

Happy to accept feedback/discussion here!