Add website nanoc source
Update .gitignore file patterns
Elaboration on sum types & add placeholders
Add Google Analytics tracking to layouts
Update ADT, AlgDT, AlgStr article
Minor update to ADT, AlgDT, AlgStr article
Update ADT section with minor edit
Add Disqus code; update footer style; minor article edits
Link to ADT / AlgDT / AlgDS article to "publish"
Add draft of Axiomatic Software and Testing Algebraic Properties