Fixed Viz compilation: removed CV_EXPORTS from cv::viz::Color. The macro forced instantiation of all Matx<double, 4, 1> constructors and triggered StaticAssert there.

load mesh function is finalized: color range is always 0-255 and RGB due to vtkPLYReader limitations

principal point is always set even though the intrinsic parameters are not given (center of window), fixed computation mistakes in setWindowSize in camera class

initial implementation of projection matrix, 3D to window coordinates, window coordinates to 3D ray (not yet tested)