Add LegendReport and ProcessStatus

[oschulz]

@theHenks , you can give it a first try (see example in LegendReport docstring).

[theHenks]

That is perfect for me. Just one small question: What is the preferred way to write to Markdown. Something like that?

open("report.md", "w") do io
    println(io, report)
end

Because I think it would be nice to include a write function, e.g.

write("report.md", report)

[oschulz]

To write Markdown to disk, that would be

open("report.md", "w") do io
    show(io, MIME"text/markdown"(), report)
end

but we can add a convenience function, of course.