Nick's initial priorities for Tor 0.2.2:

NOTE 1: I'm not looking at fiddly little stuff from TODO.021 yet.  We
        can do a step where we triage the nice-to-have issues.

NOTE 2: It's easy to list stuff like this with no time estimates and
        no target dates.  I think we should pick a target date for
        0.2.2, figure out how long the stuff we want will take, and
        triage accordingly, or vice versa.

- Design
  - Begin design work for UDP transition; identify areas where we need to
    make changes or instrument stuff early.

- Performance, mostly protocol-neutral.
  - Work with Libevent 2.0's bufferevent interface
    - Identify any performance stuff we need to push back into
      libevent to make it as fast as we want.

  - Revise how we do bandwidth limiting and round-robining between
    circuits on a connection.

  - Revise how we do bandwidth limiting and round-robining between
    connections.

  - Better flow-control to avoid filling buffers on routers.

  - Split AES across cores if possible.
  - Split SSL across cores (reach; may require Libevent 2.1).

  - Figure out good ways to instrument Tor internals so we can tell
    how well our bandwidth and flow-control stuff is actually working.

- Features
  - Proposals to implement:
    - 146: reflect long-term stability
    - 147: Stop using v2 directories to generate v3 votes.

  - Proposals to improve and implement
    - 158: microdescriptors

  - Proposals to improve and implement if not broken
    - IPv6 support.  (Parts of 117, but figure out how to handle DNS
      requests.)
    - 140: Directory diffs
    - 149: learn info from netinfo cells.
    - 134: handle authority fragmentation (Needs more analysis)

- Deprecations
  - Make .exit safe, or make it off-by-default.