keyword: specific regular expressions depending on read mode
More safeguarding against accidental (un)expansion:
Reading filelog: act only on \$(kw1|kw2|..)\$ as keywords are always
stored unexpanded.
Reading wdir: act only on \$(kw1|kw2|..): [^$\n\r]*? \$ as we only
are interested in expanded keywords in this situation.
Note: we cannot use ..): [^$\n\r]+? \$ because e.g.
the {branch} template might be empty.
hg record is a special case as we read from the working directory and
need one regex each for modified and added files. Therefore test
recording an added file.
This way we finally also forbid sequences like $Id: $ being treated
as keywords.
.. Common link and substitution definitions.
.. |hg(1)| replace:: **hg**\ (1)
.. _hg(1): hg.1.html
.. |hgrc(5)| replace:: **hgrc**\ (5)
.. _hgrc(5): hgrc.5.html
.. |hgignore(5)| replace:: **hgignore**\ (5)
.. _hgignore(5): hgignore.5.html