TTFB info in regular output

In #844, TTFB was added to JSON output. I see no reason this should not also be added to the regular output. Same with histograms - though this may be useful to have behind a flag. Might also be useful to have it visible in the live/in progress view under similar flags. Or some more verbose mode that just acts as a catch-all for all new stats added.

We already have the ability to add breakdowns of timings by response code. To me it seems reasonable to have TTFB working with all of these stats/categories.