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.
if possible, can you replace all the CvMat and cvFoo with cv::Mat and cv::foo? Also, please, put all this code into "cv" namespace and then remove all the "cv::" prefixes. This will make the code much cleaner