Add warning about Apple's weird Clang version.
Print warning on OSX when using old libstdc++ (rather than libc++).
Merge branch 'master' of https://github.com/kentonv/capnproto
Automatically add -stdlib=libc++ if system C++ library doesn't support C++11 (needed on OSX).
Document how to build on OSX.
More Mac notes.
Add note about installing autotools.
Mention how to get Xcode cli tools.
Fix comment.
Don't document inlines.