feat: Handles case where we overflow void elements.

[damencho]

Handles more tags and tracks.

[damencho]

We heavily depend on the RandomAccessFile from FileDataWriter.

So I suggest dropping DataWriter, always using FileDataWriter, and getting rid of isSeekable.

@bgrozev WDYT?

[damencho]

Well there is some logic behind isSeekable() ... my current changes may break that ... but works for our case though and I have added some tests that cover this.

[damencho]

Looking at the code that I removed:

long len = tagsElem.writeElement(ioDW);
    if (ioDW.isSeekable())
    {
      new VoidElement(BLOCK_SIZE - tagsElem.getTotalSize()).writeElement(ioDW);
      return BLOCK_SIZE;
    }

Seems that the logic of isSeekable is that if it is not seekable you do not add void element, as you will not be able to seek and come back and fill it.
And the MatroskaFileWriter.close is processing the file only when isSeekable is true, so no problem there.

[bgrozev]

The +2 is only necessary to make line 135 work? Can we simplify?

[damencho]

Actually no idea why it is there. I dropped it.