refextract: improvements to author recognition
- support for the unicode character 's' with a tilde
- support for volume numbers separated with a hyphen
- making sure that the first author in an author group, if starting with an 'A' initial, must have a full-stop after that first initial
- support for hyphens between initials
- support for a separated surname 'prefix'
- looking for bad 'et al' placement (before an author group rather than after), which causes the author group to be ignored
- arXiv suppression: removing 'arxiv' or 'e-print arxiv' before a report number and after a title
- ed. ==> eds?.
- corrected placement of 'et al' and the last 'ed.' pattern (reversed)
- support for author groups in brackets
- fixes the problem with multiple report number splitting in a single reference line (introduced in ff97c0942af09d9298b70f0934582ac05a75dc65)