FAST, oFAST and rBRIEF

### TO DO :

Replace the variables `keypoints`, `scales`, `orientations`, `response` with `kpts_recarray`:
```p
    keypoints = np.array(np.dstack((row, col, octave, orientation, response)),
                         dtype=[('row', np.double), ('col', np.double),
                         ('octave', np.double), ('orientation', np.double),
                         ('response', np.double)])
    kpts_recarray = keypoints.view(np.recarray)
```