1.2.1-alpha

Changelog:
Add more unit-tests
Fix incorrect variable names
Rename acks to packetAcks to clarify their origin
Move PacketHeader creation to PacketHeader class
Fix message deduplication
Fix MessageTypeId not being set for received messages

Also published via nuget:
https://www.nuget.org/packages/ReliableUdp/1.2.1-alpha