Clang 5.0 fixes

- Added override keyword
- Removed inherited member variables

src/Protocol/Authenticator.h

@@ -37,7 +37,7 @@ class cAuthenticator :
 
 public:
 	cAuthenticator(void);
-	~cAuthenticator();
+	virtual ~cAuthenticator() override;
 
 	/** (Re-)read server and address from INI: */
 	void ReadSettings(cSettingsRepositoryInterface & a_Settings);

src/Protocol/MojangAPI.cpp

@@ -215,7 +215,7 @@ public:
 	{
 	}
 
-	~cUpdateThread()
+	virtual ~cUpdateThread() override
 	{
 		// Notify the thread that it should stop:
 		m_ShouldTerminate = true;

src/Protocol/ProtocolRecognizer.h

@@ -45,7 +45,7 @@ public:
 	} ;
 
 	cProtocolRecognizer(cClientHandle * a_Client);
-	virtual ~cProtocolRecognizer();
+	virtual ~cProtocolRecognizer() override;
 
 	/** Translates protocol version number into protocol version text: 49 -> "1.4.4" */
 	static AString GetVersionTextFromInt(int a_ProtocolVersion);