added introduction and basics section
Began work on Basics section.
repeating pdflatex step for default make target. Once we add labels and references, we must compile twice to get them to resolve properly.

I'm not sure if there's a better way to do this, but this works for now.
routine work. tweak basics section, major work on elliptic curve stuff.

strategy going forward is to do elliptic curve section, then use this to determine what needs
covering in the earlier sections.