- functionality
  - finish serialization
  - default values
  - extensions
  - MessageSet
  - create msgdef with subset of fields

  - lazy parsing
  - strings by reference

  - enums with 0 (is this already fixed?)
  - text format to string (not just FILE*)
  - python
    - _list() accessor
    - expose enums
- tests
  - event parser
  - round-trip encode/decode
  - tree manipulation
  - memory management
- benchmarks
  - low-level encoding/decoding
  - event parsing
  - python
- checkin suite
  - benchmark diff (done)
  - memory footprint diff
  - binary size diff
  - valgrind check
  - -Werror no compiler warnings
  - test suite
  - verify that all headers compile with C++.
- misc
  - handle streaming where strings span buffer boundaries
  - expose an unknown field callback