Update to Saprus 0.2.1

Handle management messages instead of letting them bubble up through the
connection to the consumer.
Right now, this just means handling ping messages by sending a pong.

Also updated to follow the new handshake flow.
The sentinel will mirror the ports instead of matching them.

Now filters on the full source and dest ports, which are less likely to
have erroneous matches.

src/root.zig

@@ -19,7 +19,6 @@ pub const Connection = @import("Connection.zig");
 
 const msg = @import("message.zig");
 
-pub const PacketType = msg.PacketType;
 pub const MessageTypeError = msg.MessageTypeError;
 pub const MessageParseError = msg.MessageParseError;
 pub const Message = msg.Message;