GENERATE_FEATURE_TRACK generates a feature track from a list of images. Input: filelist - (mx1) struct array, containing filenames of images with its field 'name', which is the output of 'dir' command. Output: featx - image points x-coordinates (nxm) featy - image points y-coordinates (nxm) vis - visibility map (nxm) color - color of points in RGB (nx3)