fix TODO and use Log mechanism to report table-design and runtime

[sjanssen2]

previously, I directly printed the table design and runtime information to standard error. However, we do have a great logging mechanism which we should use here. Thus, the user can pick a log level and see this message depending on this log level on std::cout

[kmaibach]

Which log level do I have to select to get this message printed?
And could we include that information in the help page (or any other documentation place) somehow?

[sjanssen2]

I agree, documentation is our weak spot. However, I wonder what the best place would be to hint towards this feature?

[kmaibach]

That's a good question. As I don't know any other place, the help page is the only thing I can think of. But since this "warning" is quite important I believe it should be mentioned somewhere that's easily accessible.
Or - and that would mean quite a lot of work - we start writing a detailed documentation where the help page can reference to.