- Introduce "feature macros" WITH_DOCTYPES, WITH_ENCODINGS, WITH_HTML_OBJECT, WITH_TINPOT.
- Report them in versio output of `markdown`.
- Consistent and incredible ugly version string: "2.1.7/<http://github.com/tin-pot/discount>".
- Use WITH_TINPOT to mean the disjunction of all feature macros.
- Trying to eliminate some gratuitous differences to `orc/discount` in `mkd2html.c`.
- Clean up the feature macro mess a bit.
Fix oversights in `mkd2html.c`.
Update README and CHANGES and posc/README text and html.
Update `*.md` text versions (for github).