Proposal: Add `Higuera-Cary` to the list of allowed values for `particlePush` attributes

[steindev]

The Higuera-Cary pusher is a few years old by now, thoroughly tested and implemented by WarpX, PIConGPU and possibly others.

It is probably time to admit its existence :smile:

See

• Higuera's article on arxiv
• Riperda's comparison of relativistic particle integrators
• And the errors in printed formulas spotted by the WarpX team: (https://github.com/ECP-WarpX/WarpX/issues/320)

[ax3l]

Thanks for documenting this. I had it on the radar and thought I made an issue for it already, but this seems to not be the case yet. Done now! :)