Ref T2183. Introduces a new View which can (in theory) unify the Revision, Diff and Commit table of contents views.
This has the same behavior as before, but accepts slightly more general primitives and parameters and has somewhat cleaner code.
I've made one intentinoal behavior change: removing the "Open All in Editor" button. I suspect this is essentially unused, and is a pain to keep around. We can look at restoring it if anyone notices.