protobuf/TODO

- functionality
  - finish serialization
  - text format to string (not just FILE*)
  - default values
  - enums with 0
  - python
    - _list() accessor
    - expose enums
- tests
  - event parser
  - round-trip encode/decode
  - tree manipulation
  - memory management
- benchmarks
  - low-level encoding/decoding
  - event parsing
  - python
- performance
  - strings by reference
- 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++.