cellUpdate listener doesn't emit correct data

[agritheory]

Under test in FAB, editing any cell only yields the first argument, which is the column index.

[Alchez]

@agritheory What does the usage look like in FAB exactly? Is it similar to the example shown in #213?

Currently, the cellUpdate emit is setup to return with 4 argument values (colIndex, rowIndex, newCellValue, prevCellValue) rather than a single argument value (possibly an object).

• If you're only getting the colIndex even after trying to accept 4 argument values, then that's a bug.
• If the API expectation is to receive an object with the changed parameters, then I can make the modifications accordingly.