New C++ wrapper: cpp-prototype

This C++ API prototype was originally developed in an academic project as a device mini-framework and Kinect driver inspired by libfreenect and OpenNI 2.  I've since wrapped the header around libfreenect.h and whipped it into shape for release.

cpp prototype manages contexts, devices, and streams gracefully so you don't have to.  The built-in event thread keeps devices open and streams running only when your application is using them.  The libfreenect.hpp header is heavily-documented and cpptest.cpp demonstrates basic usage.  I also have a graphical example using Qt.  If there's any interest, I'll dust it off and add it here.

Note: To compile the cpptest example, you need [boostorg/signals2](https://github.com/boostorg/signals2) (header-only) and a compiler that supports "-std=c++0x".  I used g++ 4.6.3.  OSX users should probably use clang++.


Signed-off-by: Benn Snyder <benn.snyder@gmail.com>