octave compatibility

[yarikoptic]

to be noted in README and tested (see #2 ;) ) more, but it seems to work! It is still running but seems to be doing the "right thing" (even showed some plot):

(git-annex)hopa:~/proj/misc/motion_energy_matlab[master]demo
$> octave --eval "addpath('..');addpath('../utils'); addpath('/usr/share/octave/packages/image-2.6.1/'); ComputeMotionEnergy" 
warning: function /usr/share/octave/packages/image-2.6.1/im2double.m shadows a core library function
Converting color space ... [rgb2lab]
.....2700/2700 done. (6.2 sec) 
Done.
[[zero mean stimuli]]
Making a list of gabor parameters... channel num: 6555
Preprocessing...
....................1000/6555 done. (9.8 sec) 
....................2000/6555 done. (22.2 sec) 
....................3000/6555 done. (28.7 sec) 
....................4000/6555 done. (35.8 sec) 
....................5000/6555 done. (47.6 sec) 
....................6000/6555 done. (54.1 sec) 
...........6555/6555 done. (57.7 sec) 
Wavelet preprocessing done in 1.0 min (cputime).
6555 channels, 2700 samples
Processing static output nonlinearity... done.
Final matrix size (images x features):
    180   6555
channel num: 6555
Making wavelets...
....................1000/6555 done. (1.3 min) 
.......

$> octave --version
GNU Octave, version 4.2.1

debian sid amd64