Make summarize useful to data producers other than rustc#116

Merged

wesleywiser merged 2 commits intorust-lang:masterfrom wesleywiser:two_small_features

Jun 24, 2020

+79-32

Commits on Jun 23, 2020

Allow summarize to be used with data sources other than rustc
wesleywiser
committed

Commits on Jun 24, 2020

Hide optional columns without values
wesleywiser
committed