Update WorkflowManager for Upcoming Changes...

... those being the changes that will allow runtime voice-combination
selection for interval n-grams.
Add "Global" Settings to Be Used for Interval N-Gram Indexing
Rewrite WorkflowManager._two_part_modules()

Now it uses all the settings, and only works on one piece.
Rewrite WorkflowManager._all_part_modules()...

... now it pays attention to settings, and only works on one piece at a
time, as expected.
Cleanup to Workflow-Related Files

As recommended by pylint!