Line breaks in citations cause failed capturing of bib keys

[birnstiel]

natbib citations such as

\citep[see also][]{Aauthor2019,Bauthor2020}

are not correctly recognized if a line-break occurs. Some authors/text editors might hard-wrap this citation at the space:

Lorem ipsum dolor sit amet, consectetur adipiscing \citep[see
also][]{Aauthor2019,Bauthor2020} eget risus sollicitudin neque
imperdiet suscipit. 

adstex fails to detect those bib keys.

[yymao]

@birnstiel Thanks for reporting the issue. I have made an attempt to fix this issue in #23. If you can test the pull request that'd be great. I'll also test it and, if things go well, make a release later today.

[birnstiel]

wow that was fast! it works for my case.