Tool for identifying dead code

Launchpad is really big. So big, that there's probably a fair chunk of Launchpad's code that's not used at all ever. It would be really nice to get rid of it.

Since we have a fairly comprehensive test suite, we could write a tool that did something like:
  - run the test with the --coverage flag. Since this takes a very long time, it would probably need to be done on a server or cloud instance.
  - parse the output, looking for entire functions (blocks?) that are uncalled
  - print these functions in a nice way, preferably one that's easy to jump to in Emacs

The tool would probably need a way of letting the user identify that a function should be kept, even though it's uncalled.