AVCamManual: Extending AVCam to Use Manual Capture API

Last Revision:	Version 3.1, 2016-09-15 Adopt AVCaptureDeviceDiscoverySession (Full Revision History)
Build Requirements:	Xcode 8.0; iOS 10.0 SDK or later
Runtime Requirements:	iOS 10.0

AVCamManual adds manual controls for focus, exposure, and white balance to the AVCam sample application.