Improving grammar snippets in Python docs (53)

Approximate timestamps:
00:10:00 Tokenizer: empty lines are not NEWLINES
00:20:00 learn about diff –word-diff
00:25:00 Review related issues prior to opening a PR
00:30:00 Open a PR
00:45:00 Using COPR to build for Fedora
01:00:00 Switch to Sphinx .. production-list:: PR
01:15:00 Describe the problem and plan
01:24:00 Trick for checking the first char of a line: if source_line is None or not source_line[:1].isspace(): to avoid getting an error for blank lines (??)
01:40:00 Fixed issue gh-116666, add glossary entry for lexical analyzer and discussed improvements to prose.