Disable CSV export by default?

[PhilippWendler]

Right now we always write HTML and CSV tables unless specified otherwise. This is nice for discoverability of the CSV export because users will immediately see it in the log. However, I suspect that quite often the CSV export is not needed, and that actually the use cases where one wants both HTML and CSV are even more rare (when using table-generator in scripts for data analysis, probably the HTML is irrelevant).

So we could change it such that the CSV export is disabled by default, but if the user does not specify the --format option we print a log message with something like "Writing out tables in HTML format by default. Use --format for additional formats like CSV and TeX." This would even improve discoverability of the TeX export.