- load OBJ file
- set offscreen rendering
- set roll angle of the camera
- get Mat screenshot of the current scene
- remove all lights from the scene
- add a custom light in the scene
- modify the size of the WImage3D widget
- added ambient property for the widget

Changed Vec3d in cv::viz::Color

Renamed method getMatScreenshotin getScreenshot

Modified showWidget

Fixed on viz::Color and reverted fix on vtkProp3D

Removed cameraRoll method

Merged load mesh method (for ply and obj file)

Fixed doc

Fixed cv::viz::WImage3D::setSize for vtk5.8

Fixed enum for cv::viz::Mesh::load

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)