Handle accented characters in Citations properly, if possible at all

As of now, accented characters in citations are replaced with similar characters without accents (Schäfer becomes Schafer and Alléné becomes Allene).

According to https://git.ligo.org/computing/sccb/-/issues/1808#note_1467897, C. Alléné wants that the accented characters are used in the Circular if possible at all. Also, Schafer is not a good approximation of Schäfer, if accented characters cannot be used it should be spelled Schaefer.