Merge pull request #65 from istathar/bump-program

Bump to latest core-program

Use unbeliever packages from Hackage

Merge branch 'zero-timer'

Complete switch back to Inkscape

Emit PDF metadata

Via the **hyperref** package (why oh why?) we set various metadata
fields for the resultant PDF indicating the version of **publish** that
was used and that we are now rendering via lualatex.

Merge branch 'chapter-to-section'

Bump version to 2.1 reflecting semantic change of our treatment of first level
headings as sections rather than chapters.

Update .book file format to v2

Fix use from Docker-on-Mac

Offer --temp option

First release on Hackage