bugfix nested arrays with empty strings filled by the next array item

[kaue]

Status

READY

Description

fixes #65, an issue with empty strings in nested arrays getting filled by the next array item
also includes a minor refactoring of fillRows function

Steps to Test or Reproduce

jsonexport([
    {
        "day": "1",
        "time": "12:00",
        "persons": [
            {
                "name": "Bob",
                "lastname": "Smith"
            },
            {
                "name": "James",
                "lastname": "piet"
            },
            {
                "name": "",
                "lastname": "Miller"
            },
            {
                "name": "David",
                "lastname": "Martin"
            }
        ]
    }
], (err, csv) => {});

[AckerApple]

This new code is accurate for the issue we are chasing. Installed this branch into demo and tested there. Attaching results

day,time,persons.name,persons.lastname
1,12:00,Bob,Smith
,,James,piet
,,,Miller
,,David,Martin

Merging and will run deployment