Add a callback for when the selected items are changed?

[tgolen]

In order for code to react appropriately to a change in the selectedIds array, I feel it is necessary to add an optional callback to the options called onSelectionChange. This would be a callback that is passed the current array of selectedIds and triggered from _toggleSelectAll() and _toggleSelectRow().

I was not able to find any way of getting the selectedIds, but if I missed it for some reason, please point me to it.

Example usage:
When the selected items are changed, disable/enable a button depending on if you have any items selected or not.

if (this.props.onSelectionChange !== null && _.isFunction(this.props.onSelectionChange)) {
    this.props.onSelectionChange(newSelectedRowIds);
}

[ryanlanciaux]

See - #508 👍