pending
   - Don't eval the control expression of the first #if of a block when
     already in a false block; it might not be valid. Reported by
     Baptiste Daroussin.
   - Don't recognize comments within character constants.
   - Don't recognize macro argument parentheses or commas within strings,
     or within character constants either.

release 0.2 (20130611)
   - auto-recognize more builtin PowerPC and mips macros
   - pass -Wunused (partly from Baptiste Daroussin)
   - allow absolute paths in include files (partly from Baptiste Daroussin)
   - don't use getprogname() in the name of portability
   - add tests arising from December 2010 tech-toolchain thread (one
     from der Mouse, one of mine)
   - clean out usage of sys/cdefs.h macros and don't use the implementation
     namespace
   - make -Wcomment work again
   - fix handling of relative includes
   - provide a man page
   - other minor improvements

release 0.1 (20130610)
   - first release, works with at least some imake templates