----------------------
--- IMPORTANT TODO ---
----------------------
- provide example rpc
- at least include extensions in Descriptor
- implement default values for most primitive types,
  but not strings, bytes, or messages.

--------------------
--- NEEDED TESTS ---
--------------------
- test:
  - service method lookups
  - out-of-order fields in messages (ie if the number isn't ascending)
  - gaps in numbers: check that the number of ranges is correct
  - default values

---------------------
--- DOCUMENTATION ---
---------------------
Document:
  - __INIT macro; explain current lifetime policy
  - services
  - default value handling
    - note that the plan is to set the value to the default 
      for optional types, but NOT set has_* to TRUE.
      That way, code can just ignore the has,
      but we won't superfluously serialize the default value.
      (Move this to the docs)
      Also, for now, we won't init default values that require allocation.
    - add to CAVEATS: defaults for messages, strings, bytes not initialized
      by INIT macro.  Rationale:  would interfere with other allocator
      systems... not clear if that's true.
  - check over documentation again

--------------------------
--- LOW PRIORITY STUFF ---
--------------------------
- support Group (whatever it is)
- almost no code generator options are obeyed
- generate Init functions / handle default values
- proper support for extensions (not sure i get what's needed)

------------------------------------
--- EXTREMELY LOW PRIORITY STUFF ---
------------------------------------
- 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

----------------------------------------------
--- ISSUES WE ARE PROBABLY GOING TO IGNORE ---
----------------------------------------------
- strings may not contain NULs

-------------------------
--- IDEAS TO CONSIDER ---
-------------------------

- lifetime functions for messages:
   MESSAGE__INIT macro:
       for static messages, doesn't handle defaults requiring allocation.
   message__init_allocated_defaults (...)
       for static messages, only touches default values that must
       be allocated.
   message__init(...)
       initializes all defaults -- does allocations for strings etc
   message__new()
       return a new message using an allocator with standard allocation policy
   message__unpack_onto(...)
       unpack onto an initialized message
   message__clear(...)
       clears all allocations, does not free the message itself
   message__free(...)
       free the message.
  [yeah, right: after typing it out, i see it's way too complicated]