First draft of the lecture.

Some definitions from 2013-03-06 need to be added, fortunately I have
half a page of notes from that lecture.
Added the definition of the inner product on S.
Almost there.
Done.
Some more details before merging.

What does the sentence about cockroaches even mean?
Merge pull request #6 from eggrobin/lecture-2013-03-12

Lecture 2013 03 12