Merge pull request #30 from cxw42/wip

Some niceties

Merge pull request #26 from cxw42/wip

Figures, code-block formatting, special blocks

Merge pull request #18 from cxw42/issue15

Text justification; font name; space between paragraphs

Add code-coverage script, CONTRIBUTING.md

- Add script to run the code-coverage check
- Split the contributing instructions from README.md into
  separate CONTRIBUTING.md.
- Also, include the .md files and the coverage script in the dist tarball.

Merge pull request #10 from cxw42/dev

Add templates; add tests, code-coverage checks

Merge pull request #5 from cxw42/rc2

pango-markup: support images in PDFs