Add an event when profile stitching is happening

Currently it is not possible to see when profile stitching has happened. This makes it almost impossible to investigate how incorrect stitching has happened as you can only see the end result. Having an event when profiles are stitched together would help a lot in identifying the time problems may have occurred.

Being able to monitor stitching events via reports would also make it possible to identify profiles where stitching has happened incorrectly (lot of stitching events at a certain point or lot of stitching events for a single customer).