Add TrackChanges type to options.
Add reader option for track changes.
Add TrackChanges to Options export.
Add track changes option to command line.
Docx reader: Make use of track-changes option.
Updated README to include "--track-changes" option.
Track changes tests.
Fix typo in README.
Docx reader: Code cleanup in parse.

Remove some redundant ways of dealing with Maybe.
Merge pull request #1375 from jkr/cleanup

Docx reader: Code cleanup in parse.
Merge pull request #1374 from jkr/track-changes-options

Track changes with options