Change BD-Rate calculation to not include points outside the range when fitting the curve.
Change BD-Rate calculation to not include points outside the range when fitting the curve.

This makes the behavior match draft-daede-netvc-testing.

Thanks to Iole Marccagatta for finding the bug and providing the fix.

tdaede/awcy,tdaede/awcy,tdaede/awcy,tdaede/awcy,tdaede/awcy,tdaede/awcy