Git: ignore untracked files in ferret submodule
Git: ignore untracked files in ferret submodule

I have an untracked TOOD.txt file floating around in there. Let's keep
it from cluttering the `git status` output.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent