Browse history of a particular module

It would be useful to have way to see how a specific module has evolved over time (API changes etc).

I'm not entirely sure what kind of UI would be best though. On a minimal level, a simple navigation bar that links to each respective version of the same module would provide more usability than the current approach (which requires returning to the package page and then back).

A more sophisticated system would be something like git-log+git-blame, but that's a lot more involved (and has to deal with spurious changes introduced by Haddock changes).