Macro cleanups/fixes and enable C++14 for tuple addressing via type
Bundled library updates & iOS fixes

* Update bundled libpng, libc++, and BTstack
* makeAll-* scripts now always perform the install target to prevent issues when a bundled lib has a dependency (libvorbis with libogg for example)
* Note GCC 4.9 requirement in install docs
* Guard iOS > 4.0 API calls in ARMv6 build
* Convert remaining NSNotificationCenter addObserver calls to use blocks