Motivation:
At the moment its a bit "hacky" to retrieve the hostname that was used during SNI as you need to hold a reference to SniHandler and then call hostname() once the selection is done. It would be better to fire an event to let the user know we did the selection.
Modifications:
Add a SniCompletionEvent that can be used to get the hostname that was used to do the selection and was included in the SNI extension.
Result:
Easier usage of SNI.