Start refactoring protocol code into sub package. Move Packet Encoding and list of Commands. Change SetSelfReportedPorts parameters.

More related commits to follow!

protocol/Hash.go

@@ -0,0 +1,18 @@
+/*
+File Name:  Hash.go
+Copyright:  2021 Peernet s.r.o.
+Author:     Peter Kleissner
+*/
+
+package protocol
+
+import "lukechampine.com/blake3"
+
+// HashData abstracts the hash function.
+func HashData(data []byte) (hash []byte) {
+	hash32 := blake3.Sum256(data)
+	return hash32[:]
+}
+
+// HashSize is blake3 hash digest size = 256 bits
+const HashSize = 32