DynamicAperture Softening parameter is dependent on the pixel scale

[LouisDesdoigts]

The softening parameter is meant to be agnostic to the physical scale of the aperture itself, but this is not the case.

Example:

import dLux as dl
import matplotlib.pyplot as plt

radius = 1e-6
aper = dl.CircularAperture(1e-6)
plt.imshow(aper.get_transmission(256, 2*radius))

We need to set softening to a very small value to get sensible results

aper = dl.CircularAperture(1e-6, softening=1e-5)
plt.imshow(aper.get_transmission(256, 2*radius))

This will be an issue for coronagraphs that have small angular pixel scales in the occulter plane.

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[LouisDesdoigts]

@Jordan-Dennis would love your thoughts. I briefly tried to add a scale parameter to the _soften method taken from the coordinates but it seems the solution will be a little more involved than that.

[LouisDesdoigts]

Fixed with #246