Add "changeType" to onChange() function #391

Hello,

Could you add an extra parameter to the onChange() function prop for the <Spreadsheet> component that specifies in the manner the data was changed? i.e. if the change was caused by typing, pasting, deleting, etc?

I have some data cleanup that needs to happen when information is pasted into the spreadsheet, but not when values are being typed in by hand.

Thanks!