Show revision sizes using a perplexing, inexplicable symbol code

Summary: Ref T13110. See PHI230. Show revision sizes on a roughly logarithmic scale from 1-7 stars. See D16322 for theorycrafting on this element.

Test Plan: Looked at some revisions, saw plausible-looking size markers.

Maniphest Tasks: T13110

Differential Revision: https://secure.phabricator.com/D19294