Add tooling to make it easier to write a frontend. Or at least define a schema

[AriSweedler]

From #23, I see that you write an awk script to convert shell output to groovy code (the groovy code is what codes for freeplane graphs)

As is, one can write a compiler in any language, it doesn't have to be awk. However, the only accepted target data format is groovy code. It would make more sense to me if I could target a schema. Like let's say we choose JSON to implement theschema. So then instead of shell output --awk--> groovy it would go shell output --anything(targets schema)--> JSON data structure --compiler--> groovy.

What is the schema? I would love to write some frontends for some of my favorite commands. I would target the schema you told me about. I could also try and take the schema and write a backend that will generate the groovy from the schema.