Add warning

[WenzDaniel]

Add a small user warning if a plugin is deregistered as this is should be not a normal use case. Also converts list of plugins to deregistered into a set to avoid duplication. Small addition to: https://github.com/AxFoundation/strax/pull/775/files

[github-actions]

coverage: 91.123% (-0.3%) from 91.472%
when pulling c0cecbb on add_warning
into 672dacb on master.

[coveralls]

coverage: 91.352% (+0.002%) from 91.35%
when pulling 0383f06 on add_warning
into e102dbb on master.

[JelleAalbers]

This is a good idea; I had this in #775 earlier but it generated quite a few messages when starting a cutax context. But maybe that's OK, or you want to merge this after fixing straxen/cutax first.

[WenzDaniel]

For straxen I did: XENONnT/straxen#1292
For cutax this is a bigger story because we are auto-registering cuts which we should not do in my opinion. But should be solved with: https://github.com/XENONnT/cutax/pull/317 I think.

[JelleAalbers]

Looks good! I assume you want to wait until at least https://github.com/XENONnT/cutax/pull/317 is merged to avoid a swarm of warning messages, but from the strax side I don't see any problems.

(Well, there is a typo in the message, overlap dregister should probably be overlaps registered, but I guess it reinforces the message that you should not be seeing this message ;-)

The set doesn't change any behavior I think due to the check if old_plugin == currently_registered, but I think it make things clearer. (The purpose is to deregister plugins once for each datatype.)

[WenzDaniel]

Thanks @JelleAalbers, I fixed the typo. Regarding the set, I was under the impression that otherwise the error is raised multiple times, but I could be wrong now.