Log Message:
lowdown: update to 0.4.6.

ChangeLog:

lowdown 0.4.6:

- Make sure stdint is everywhere.

lowdown 0.4.5:

- Use BSD.lv's mandoc.css.
- Use BSD.lv's style and clean up.
- Newest sblg.
- Add stdint.

lowdown 0.4.4:

- Use Makefile.configure's macros.
- Bring up to speed w/other bsd.lv sites.
- Newest oconfigure.
- Document list-start for commonmark.
- All outputs process start list item for commonmark.
- Capture list start iff commonmark.

lowdown 0.4.3:

- Add atom version feed.
- Use new oconfigure.
- Bound reading into the value buffer.

lowdown 0.4.2:

- Document maths.
- Remove MATHEXP ("mathexp") facility.
- Disable MATHEXP mode. This offers nothing, but ends up complicating
  the user experience. Stick with only one "math mode" and document it
  properly.
- Have math blocks reported in -Ttree and accumulate the content in a
  text node.
- Begin incorporating better math mode.
- Fix pdfhref links in lists.
- In nroff mode, stretch table to fit width and embolden header.
- Add table documentation.
- Typo found by Anton Lindqvist.