Clean up the use of version numbers in filenames; always use an "abstract" version number, and explain what it is at the top of the chapter. This closes SF bug #225003.
Clean up the use of version numbers in filenames; always use an "abstract"
version number, and explain what it is at the top of the chapter.
This closes SF bug #225003.

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