Added OIS_UNUSED to silence unused variable warnings

Also added some other helper macros:
* OIS_INLINE_PRAGMA
* OIS_MACRO_BEGIN
* OIS_MACRO_END

includes/OISJoyStick.h

@@ -148,13 +148,13 @@ namespace OIS
 
 		//-- Not so common control events, so are not required --//
 		//! Joystick Event, and sliderID
-		virtual bool sliderMoved( const JoyStickEvent &, int index) {return true;}
+		virtual bool sliderMoved( const JoyStickEvent &arg, int index) { OIS_UNUSED(arg); OIS_UNUSED(index); return true; }
 
 		//! Joystick Event, and povID
-		virtual bool povMoved( const JoyStickEvent &arg, int index) {return true;}
+		virtual bool povMoved( const JoyStickEvent &arg, int index) { OIS_UNUSED(arg); OIS_UNUSED(index); return true; }
 
 		//! Joystick Event, and Vector3ID
-		virtual bool vector3Moved( const JoyStickEvent &arg, int index) {return true;}
+		virtual bool vector3Moved( const JoyStickEvent &arg, int index) { OIS_UNUSED(arg); OIS_UNUSED(index); return true; }
 	};
 
 	/**

includes/OISPrereqs.h

@@ -99,6 +99,26 @@ restrictions:
 #	define OIS_ARCH_32
 #endif
 
+//-------------- Various helper preprocessor definitions ---------------------//
+
+#ifdef OIS_MSVC_COMPILER
+#	define OIS_INLINE_PRAGMA(x) __pragma(x) // x is intentionally not wrapped; __pragma rejects expressions beginning with '('.
+#else
+#	define OIS_INLINE_PRAGMA(x)
+#endif
+
+#define OIS_MACRO_BEGIN do {
+
+#define OIS_MACRO_END \
+	} OIS_INLINE_PRAGMA(warning(push)) OIS_INLINE_PRAGMA(warning(disable:4127)) while (0) OIS_INLINE_PRAGMA(warning(pop))
+
+// This creative trickery taken from this StackOverflow answer:
+// http://stackoverflow.com/questions/4030959/will-a-variablename-c-statement-be-a-no-op-at-all-times/4030983#4030983
+#define OIS_UNUSED(x)\
+	OIS_MACRO_BEGIN\
+		((void)(true ? 0 : ((x), void(), 0)));\
+	OIS_MACRO_END
+
 //-------------- Common Classes, Enums, and Typdef's -------------------------//
 #define OIS_VERSION_MAJOR 1
 #define OIS_VERSION_MINOR 4

includes/win32/Win32KeyBoard.h

@@ -60,7 +60,7 @@ namespace OIS
 		virtual void capture();
 
 		/** @copydoc Object::queryInterface */
-		virtual Interface* queryInterface(Interface::IType type) {return 0;}
+		virtual Interface* queryInterface(Interface::IType type) { OIS_UNUSED(type); return 0; }
 
 		/** @copydoc Object::_initialize */
 		virtual void _initialize();

includes/win32/Win32Mouse.h

@@ -41,7 +41,7 @@ namespace OIS
 		virtual void capture();
 
 		/** @copydoc Object::queryInterface */
-		virtual Interface* queryInterface(Interface::IType type) {return 0;}
+		virtual Interface* queryInterface(Interface::IType type) { OIS_UNUSED(type); return 0;}
 
 		/** @copydoc Object::_initialize */
 		virtual void _initialize();

src/OISInputManager.cpp

@@ -266,6 +266,8 @@ void InputManager::removeFactoryCreator( FactoryCreator* factory )
 //----------------------------------------------------------------------------//
 void InputManager::enableAddOnFactory(AddOnFactories factory)
 {
+	OIS_UNUSED(factory);
+
 #if defined OIS_LIRC_SUPPORT
 	if( factory == AddOn_LIRC || factory == AddOn_All )
 	{

src/win32/Win32InputManager.cpp

@@ -230,6 +230,8 @@ bool Win32InputManager::vendorExist(Type iType, const std::string & vendor)
 //----------------------------------------------------------------------------//
 Object* Win32InputManager::createObject(InputManager* creator, Type iType, bool bufferMode, const std::string & vendor)
 {
+	OIS_UNUSED(creator);
+
 	Object *obj = 0;
 
 	switch(iType)