Affine inverted x and y

[giovannivolpe]

In dt.Affine (which applies any affine transformation to an image), the x and y positions are defined the opposite way from the rest of deeptrack. I.e. dt.Affine(translate=(4, 0)) on an image with an object at (32, 32) would result in an object at (32, 36). This should be corrected at some point.