Encryption fixed
Removed dead code (SenderChannelBase.cs)
Added LibrarySamples/EncryptionSample
Added NetConnection.CanSendImmediately() to determine if the sliding window is full
Recycle outgoing dropped messages
Encryption using CryptoProviders refactored 
Added NetUnreliableSizeBehaviour to configure behaviour for unreliable messages above MTU
Debug stats show number of received fragments
Don't try to parse packets identified as UPnP responses even when UPnP response parsing fails