Fixed a lot of the smaller nits identified in Guido's comments.
Fixed a lot of the smaller nits identified in Guido's comments.

Filled in some of the "blank" areas, and added another large blank
area for a LaTeX primer.  (Still a lot to be done.)

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator