with-parser: Fix srcloc
Fix typos in comments
Ensure \r\n -> \n for parser.

I misread the docs for `#:mode 'text` -- that only works on Windows.

This was compounded by my not noticing that Emacs was doing \r\n -> \n
automatically when I would copy and paste fragments from a file with
\r\n, and those would of course work.
Use new `manyUntil` from Parsack.

Required for the `lookAhead` in `flexi` to work properly in all cases,
so that our optional closing tag logic actually works.
Convert <lj-cut> elements to <!-- more -->

Also tolerate badly formed HTML with lj-cut tags, by discarding the
close tag. We only care about the open tag position, anyway.
More unit tests.
Bump to v0.12