Creates list of items found in rows, where these rows match a value in another column.
Think of it as multiple VLOOKUPs, but concatenated and return output as list with custom separator.
Pass workbook, sheet name, and separator as usual with most of my functions.
Edit 2020-05-27: Adding ability to result in unique list, by adding flag (UniqueList = 1), default is not unique.
The return is not a Unique list, we can add that (note commented lines) in future versions.