Pixel Swapper Function

[robelgeda]

When an intensity model is shifted by a small amount, the center of the model is not sampled onto a grid. Even using scipy quad integration, the pixel value would miss the center for high index profiles. Thus there should be an option to swap the nearest pixel (especially in oversampling mode) with the value of the center of the model. Most models have a x_0 or x_mean attribute that we could use to swap pixels (this would be "smart swapping" or "auto" mode). We can also allow the user to provide a list of parameter name tuples that represent the (x, y) coordinates.