Mark GUIControl destructor as virtual

Previously GUIControl destructor was not virtual and did not run any of
derived classes destructors. Now that it is and derived destructors are
ran, they actually double free due to `Destroy` has already been called
on the objects by `GUIControlManager::Clear`. They were also
inconsistent with some classes having them and some not, so I unified
the approach and removed the destructors in `GUIControl`-derived classes
that only called `Destroy`.

Author: janisozaur

Source/GUI/GUICollectionBox.cpp

@@ -16,10 +16,6 @@ GUICollectionBox::GUICollectionBox(GUIManager* Manager, GUIControlManager* Contr
 	m_IsContainer = true; // We are a container
 }
 
-GUICollectionBox::~GUICollectionBox() {
-	Destroy();
-}
-
 void GUICollectionBox::Create(const std::string& Name, int X, int Y, int Width, int Height) {
 	GUIControl::Create(Name, X, Y, Width, Height);
 

Source/GUI/GUICollectionBox.h

@@ -24,9 +24,6 @@ namespace RTE {
 		/// @param Manager GUIManager, GUIControlManager.
 		GUICollectionBox(GUIManager* Manager, GUIControlManager* ControlManager);
 
-		/// Destructor method used to clean up this before deletion from memory.
-		~GUICollectionBox();
-
 		/// Called when the control has been created.
 		/// @param Name Name, Position.
 		void Create(const std::string& Name, int X, int Y, int Width = -1, int Height = -1) override;

Source/GUI/GUIControl.h

@@ -22,6 +22,8 @@ namespace RTE {
 		/// system memory.
 		GUIControl();
 
+		virtual ~GUIControl() = default;
+
 		/// Called when the control has been created.
 		/// @param Name Name, Position, Size
 		virtual void Create(const std::string& Name, int X, int Y, int Width = -1, int Height = -1);

Source/GUI/GUISkin.cpp

@@ -17,10 +17,6 @@ GUISkin::GUISkin(GUIScreen* Screen) {
 	Clear();
 }
 
-GUISkin::~GUISkin() {
-	Destroy();
-}
-
 void GUISkin::Clear() {
 	m_PropList.clear();
 	m_ImageCache.clear();

Source/GUI/GUISkin.h

@@ -11,10 +11,6 @@ namespace RTE {
 		/// @param Screen GUIScreen Interface.
 		explicit GUISkin(GUIScreen* Screen);
 
-		/// Destructor method used to free a GUISkin object in system
-		/// memory.
-		~GUISkin();
-
 		/// Loads a skin for a directory
 		/// @param directory Skin directory and the file within to use
 		bool Load(const std::string& directory, const std::string& fileName = "skin.ini");

Source/GUI/GUISound.cpp

@@ -8,10 +8,6 @@ GUISound::GUISound() {
 	Clear();
 }
 
-GUISound::~GUISound() {
-	Destroy();
-}
-
 void GUISound::Clear() {
 	m_SplashSound.Reset();
 	m_EnterMenuSound.Reset();

Source/GUI/GUISound.h

@@ -22,9 +22,6 @@ namespace RTE {
 #pragma region Destruction
 		/// Destroys and resets (through Clear()) the GUISound object.
 		void Destroy() { Clear(); }
-
-		/// Destructor method used to clean up a GUISound object before deletion from system memory.
-		~GUISound();
 #pragma endregion
 
 #pragma region Getters