Improve test scripts, and add a new mega-test script which runs super-test on all platforms in parallel with progress bars.

Make sure generated code compiles cleanly even with pedantic warnings, since some people enable those.

Warn when an optimized build doesn't set NDEBUG and then #define it ourselves -- unless the build explicitly sets DEBUG.

Split libcapnp into three libraries:  libkj, libcapnp, and libcapnpc.  The third contains the schema parser.  Unfortunately it is rather enormous so we should give people the option to not link it.