Fix 'Log' and 'Edit' link URLs.
Use more verbose attribute entities.
Generate HTML5 footer information based on 'git log' information.
Condition generation of git attribute entity flags on presence of git.
Simplify SVG for MLton logo.

Unfortunately, ImageMagick and GraphicsMagick don't properly support
"use" elements.  The intention of defining the various strokes is for
reuse and experimenting with effects.
Merge pull request #25 from MatthewFluet/asciidoc-guide

Additional commits for AsciiDoc guide.