0028762: Visualization, Ray tracing - Implement depth-of-field effect

0028762: Visualization, Ray tracing - Implement depth-of-field effect

Graphic3d_RenderingParams - introduced new parameters CameraFocalPlaneDist and CameraApertureRadius managing DOF effect.
TKOpenGl - added new ray generation logic to RaytraceBase.fs.
vrenderparams command - added -focal and -aperture parameters.
OpenGl_View.hxx - function for ray generating was split into two functions (ray tracing and path tracing).
OpenGl_View_Raytrace.cxx - fixed interaction between adaptive sampling and stereo camera