Provide users with the option to keep blank rows in the column attributes table

[mbcann01]

Currently, cb_get_col_attributes() will drop Column description:, Source information:, Column type:, and/or Value labels: from the column attributes table if they don't exist. Doug requested an option to keep them in the Word document with blank values so that he could hand the Word document off to be filled out by a GRA manually.

I think this is typically a bad practice, but I don't see anything wrong with giving the option to the user.

• [x] Create unit tests
• [x] Add an example of keeping all rows in the column attributes table
• [x] Update documentation
• [x] Build check before closing

[mbcann01]

Add an example of manually creating a value label

Decided this should be a separate issue. #16