Deal correctly with non-square videos

[giovannivolpe]

In several points in the code, non-square videos are dealt incorrectly because width and height are inverted.

[hsaga]

I fixed this as well as updated other things in deeptrack.py in the branch: Edit-deeptrack

-Track non-square videos
-Fixed x,y in plot_tracked_scanning_boxes
-added option for elliptical particles in training
-fixed the resizing of the boxes in track_video (track_frame)
-added an option for preprocessing the images before tracking (normalise and enhance)

[giovannivolpe]

Ok, can you merge also this into develop?

After you have merged both, make a push request into master.
This version shdoul be exactly that that we give as SI in the article.