Added support for output type: markdown

[Dingsd4]

This may resolve issue #204

[sensslen]

@Dingsd4 thank you for this Pull request. It's highly appreciated. I would love to see tests added for this. Would you mind working on this - I may not be able to work on that for a few days....

[Dingsd4]

Shall I patch your TableOutputFormatterTest to support the new setting printMarkdown (additional parameter at TestFixture) or do you prefer a MarkdownTableOutputFormatterTest

[sensslen]

Shall I patch your TableOutputFormatterTest to support the new setting printMarkdown (additional parameter at TestFixture) or do you prefer a MarkdownTableOutputFormatterTest

I'd prefer a new test class.... Up to you though - no hard feelings either way

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Dingsd4]

Done, code coverage of new code is at 100% with one exception.
I did not add test code for the (patched) unused Create function at TablePrinter.

public static TablePrinter Create(Stream stream, params string[] headings)
{
    return new TablePrinter(stream, headings, false);
}

[Dingsd4]

The sonarcubecloud code coverage (0%) has an error:

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[Dingsd4]

Depends on #207

[sensslen]

Thank you a lot for this.