Added Godot based server

tools/server/core/Client.go

@@ -0,0 +1,17 @@
+package core
+
+import (
+	"net"
+	"time"
+)
+
+// Client represents a UDP client.
+type Client struct {
+	address    *net.UDPAddr
+	lastPacket time.Time
+}
+
+// String shows the client address.
+func (c *Client) String() string {
+	return c.address.String()
+}