- check over documentation again
- handle unknown fields when packing
- test code

- ensure enums are 32-bit
- support Group (whatever it is)
- almost no code generator options are obeyed
- ISSUE: strings may not contain NULs
- generate Init functions / handle default values
- at least include extensions in Descriptor
- proper support for extensions (not sure i get what's needed)

- get rid of kThick/ThinSeparator if we decide not to use them
- stop using qsort in the code generator:  find some c++ish way to do it