New PnP approach to calib3d module

SOLVEPNP_UPNP

Method is based on the paper of A.Penate-Sanchez, J.Andrade-Cetto, F.Moreno-Noguer. "Exhaustive Linearization for Robust Camera Pose and Focal Length Estimation".

Usng this method estimates the camera pose and the parameters fx and fy assuming that both have the same value. Then the ``cameraMatrix`` is updated with the estimated focal length.
please, place all the functionality into cv namespace. Placing "using namespace std" in headers is quite bad practice. It's better to put this in .cpp file and explicitly type std::vector etc. in the header.