Release notes: AMTMitelCRE 1.6.3.15

[Hilton Williams]

• Now handles multiple synchronisation sources in a RTP stream. The problem was that when the synchronisation source changed, the RTP sequence numbers would be reset, and this caused the missing packet detection code to think a large section of data was missing.
• Added additional code to handle missing packets using the timestamp information provided. The sequence numbers are still wrong, so this code may not handle all situations correctly.