OpenGL 2.1 is now required to use love.graphics (resolves issue #779.)

Removed love.graphics.isSupported("canvas", "shader", "npot", "subtractive", and "mipmap"), since those features are all guaranteed by the minimum system requirements.

--HG--
branch : minor

src/modules/window/Window.h

@@ -39,6 +39,14 @@ namespace window
 // whole thing here because it uses the Window::Type enum.
 struct WindowSettings;
 
+enum MessageBoxType
+{
+	MESSAGEBOX_ERROR,
+	MESSAGEBOX_WARNING,
+	MESSAGEBOX_INFO,
+	MESSAGEBOX_MAX_ENUM
+};
+
 class Window : public Module
 {
 public:
@@ -119,6 +127,8 @@ public:
 
 	virtual const void *getHandle() const = 0;
 
+	virtual void showMessageBox(MessageBoxType type, const char *title, const char *message) = 0;
+
 	//virtual static Window *createSingleton() = 0;
 	//virtual static Window *getSingleton() = 0;
 	// No virtual statics, of course, but you are supposed to implement these statics.
@@ -129,6 +139,9 @@ public:
 	static bool getConstant(const char *in, FullscreenType &out);
 	static bool getConstant(FullscreenType in, const char *&out);
 
+	static bool getConstant(const char *in, MessageBoxType &out);
+	static bool getConstant(MessageBoxType in, const char *&out);
+
 protected:
 
 	static Window *singleton;
@@ -141,6 +154,9 @@ private:
 	static StringMap<FullscreenType, FULLSCREEN_TYPE_MAX_ENUM>::Entry fullscreenTypeEntries[];
 	static StringMap<FullscreenType, FULLSCREEN_TYPE_MAX_ENUM> fullscreenTypes;
 
+	static StringMap<MessageBoxType, MESSAGEBOX_MAX_ENUM>::Entry messageBoxTypeEntries[];
+	static StringMap<MessageBoxType, MESSAGEBOX_MAX_ENUM> messageBoxTypes;
+
 }; // Window
 
 struct WindowSettings