Let users deactivate warning phrases from the options pane

[ProfJanetDavis]

Use case: I don't feel like I apologize too much, and I'd like to never get warnings on words like "sorry", "apologies", and "apologize". I should be able to see a list of all warning phrases on the options pane and uncheck the ones I don't want.

This would have the side effect of making the full list of warning phrases visible in a second location beyond the documentation, per #57.