Prompt when loading YAML files

[ghost]

Prompt user to either open in GUI or text editor, since saving changes would result in loss of formatting.

[mayacoda]

We had a discussion about this topic. Ideally cottontail should treat YAML files in the following way:

1. YAML files that are opened in text mode should stay YAML.
2. YAML files opened in GUI mode have to be converted to JSON in order to work with the editor.
3. When saving files, always save in the format in which they were loaded. This means converting JSON back to YAML if the file was edited in GUI mode. Custom formatting will be lost, unfortunately.

With regards to the first point, it should be noted that in order to have validation on CWL YAML files, we'll have to convert them to JSON and our internal CWL model before we can validate them. This conversion could potentially be super slow.

[ivanbatic]

@ntijanic @mayacoda
We can actually convert the JSON back to YAML in the almost exact same format as we read it.
Not necessarily in the near future, but there is nothing that technically prevents us from doing so, it just requires more effort, might go into a backlog of bells and whistles.

[mayacoda]

As has been discussed before, at the very least our reformatting should be deterministic, so diffs can be possible. Until we get to the point where we can reproduce the format in which the user originally wrote the document, there should be some prompt that the file will be reformatted.

Also, people really like YAML. Should YAML be the default format we convert to when going from GUI->text, if the file wasn't originally imported as a JSON?