Various fixes that I made after teaching this course twice.
1. Fix an error on slide 32 where it claims that a string
which is syntactically correct is actually incorrect.
2. Use some HTML trickery to remove some incorrect spaces that were
appearing in slides and confusing students. The spaces were there
because the writer was trying to "escape" some elements. Instead
I replaced them with the output of the markdown interpreter.
3. Slide 60 implied we had already talked about draw() when we had
not.
4. There was a small grammar mistake: let's versus lets on slide
"starter.html" was not a real starter file. Now it is.
Various fixes that I made after teaching this course twice.