Renamed Window::IsOpened to IsOpen

Made some minor consistency modifications in internal code

examples/opengl/OpenGL.cpp

@@ -57,7 +57,7 @@ int main()
     sf::Clock clock;
 
     // Start game loop
-    while (window.IsOpened())
+    while (window.IsOpen())
     {
         // Process events
         sf::Event event;

examples/pong/Pong.cpp

@@ -82,7 +82,7 @@ int main()
     float ballAngle         = 0.f; // to be changed later
 
     bool isPlaying = false;
-    while (window.IsOpened())
+    while (window.IsOpen())
     {
         // Handle events
         sf::Event event;

examples/shader/Shader.cpp

@@ -305,7 +305,7 @@ int main()
 
     // Start the game loop
     sf::Clock clock;
-    while (window.IsOpened())
+    while (window.IsOpen())
     {
         // Process events
         sf::Event event;

examples/window/Window.cpp

@@ -34,7 +34,7 @@ int main()
     gluPerspective(90.f, 1.f, 1.f, 500.f);
 
     // Start the game loop
-    while (window.IsOpened())
+    while (window.IsOpen())
     {
         // Process events
         sf::Event event;