Spent a couple of days catching up on backlog, and my backlog is down to 80
messages now. Lowest in recent memory.

Made the annex.largefiles config be honored by `git annex import`, `git
annex addurl`, and even `git annex importfeed`.

Planning to dive into smudge filters soon. The design seems ready to go,
although there is some complication in needing to keep track of mappings
between worktree files and annex keys.
