Second order SDC

Code release for the article

@misc{akramov2023spectral,
      title={Spectral deferred correction methods for second-order problems}, 
     author={Ikrom Akramov and Sebastian Götschel and Michael Minion and Daniel Ruprecht and Robert Speck},
     year={2023},
     eprint={2310.08352},
     archivePrefix={arXiv},
     primaryClass={math.NA}
}

Does also contain updates for the FEniCS examples.