As `pdftotext` can be a bit blasé about spaces, it is best not to be
too officious about them in pattern matching to find where the files
separate.
Fixed a bug wherein the anchor type in a list was not being reset,
meaning that index entries in list elements weren't being added.
Added an explicit "new segment" command to force a split at that point
(useful for when the sectioning and phantom sectioning gets it wrong).
A few more mathematical tests, trying to figure out the best
replacement for `\mathbin` and similar as these don't work in itex the
same as in TeX.