Use a better, less-truncated, PSF as default for MICADO

[hugobuddel]

The current default PSF for MICADO (https://github.com/AstarVienna/irdb/blob/dev_master/MICADO/PSF_SCAO_ConstPSF_0_5off.fits) is truncated at the edges:

The value at the left edge is 3.6e-6, and in the center it is 0.026. So the contrast is about 1:7000. Nevertheless, this still causes visible boxiness, e.g. in https://scopesim.readthedocs.io/en/latest/examples/2_multiple_telescopes.html :

Increasing the exposure time will lead to saturation which clearly shows 'boxed stars', e.g. this simulation of a crowded cluster:

It is debatable how much of a problem this cut-off actually is for scientific analysis of the simulations. As in, it only causes a problem for faint objects at the exact edge of the box, and highly saturated observations should be avoided due to persistence.

Nevertheless, it looks ugly and wastes peoples time. New users will probably encounter boxy stars in one of their first simulations.

We should therefore consider using a better default PSF. Two suggestions:

• Use AnisoCADO as default; this might be slow.
• Use AnisoCADO to create a larger PSF; this might bloat the size of the IRDB. Maybe the file could be compressed?

Thanks too @masha-astro