Remove unnecessary m_instance declarations

They don't do anything at all in gcc and clang, but cause compile errors in MSVC
see #955

src/app/app.h

@@ -407,5 +407,3 @@ protected:
 
     std::map<int, bool> m_textInputEnabled;
 };
-
-template<> CApplication* CSingleton<CApplication>::m_instance;

src/app/input.h

@@ -161,5 +161,3 @@ private:
 
     std::map<InputSlot, std::string> m_keyTable;
 };
-
-template<> CInput* CSingleton<CInput>::m_instance;

src/app/pathman.h

@@ -67,5 +67,3 @@ private:
     //! Save path
     std::string m_savePath;
 };
-
-template<> CPathManager* CSingleton<CPathManager>::m_instance;

src/common/config_file.h

@@ -112,5 +112,3 @@ inline CConfigFile & GetConfigFile()
 {
     return CConfigFile::GetInstance();
 }
-
-template<> CConfigFile* CSingleton<CConfigFile>::m_instance;

src/common/logger.h

@@ -136,5 +136,3 @@ inline CLogger* GetLogger()
 {
     return CLogger::GetInstancePointer();
 }
-
-template<> CLogger* CSingleton<CLogger>::m_instance;

src/common/settings.h

@@ -105,5 +105,3 @@ protected:
 
     Language m_language;
 };
-
-template<> CSettings* CSingleton<CSettings>::m_instance;

src/graphics/engine/engine.h

@@ -1490,5 +1490,3 @@ protected:
 
 
 } // namespace Gfx
-
-template<> Gfx::CEngine* CSingleton<Gfx::CEngine>::m_instance;

src/level/robotmain.h

@@ -716,5 +716,3 @@ protected:
     //! Index of currently selected element in command history
     int             m_commandHistoryIndex;
 };
-
-template<> CRobotMain* CSingleton<CRobotMain>::m_instance;

src/object/object_manager.h

@@ -311,5 +311,3 @@ private:
     int m_activeObjectIterators;
     bool m_shouldCleanRemovedObjects;
 };
-
-template<> CObjectManager* CSingleton<CObjectManager>::m_instance;