A warning is now issued in the case the VideoWriter could not be instantiated, advising to change the codec
This change applies to FaceLandmarkVid* and FeatureExtraction executables
The option is used as "-oc CODEC_FOURCC" and defaults to DIVX. If the user inputs a FOURCC with a size different than 4, than the default codec is used
The option is handled by the function get_video_input_output_params in the LandMarkDetector namespace
