Latex commands spanning multiple lines are broken

[albertz]

Example:

Done before \cite{paper1,
paper2,
paper3}.

I see that #51 might be related.

[sylvainhalle]

The section Helping TeXtidote in the readme alludes to this by saying:

Keep the arguments of a command on a single line.

I think we could replace the regex for citations so that it tolerates spanning over multiple lines, but it should be tested, as the implementation of AnnotatedString, as you point out, is a bit flaky.