implement server and client player join/leave notifications

include/server/handlers/PlayerLoginHandler.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <blitz/protocol/PacketHandler.h>
+
+namespace blitz {
+namespace server {
+
+class PlayerLoginHandler : public protocol::PacketHandler {
+  public:
+	PlayerLoginHandler(network::EnetConnection& a_Connection, EnttWorld& a_World);
+	~PlayerLoginHandler();
+
+	NazaraSlot(network::EnetConnection, OnPlayerLogin, m_Slot);
+
+  private:
+	void Handle(std::uint16_t, const protocol::data::PlayerLogin&);
+};
+
+}  // namespace server
+}  // namespace blitz