Handle Game Window closing by closing connection and being prepared for a new Connection

src/main/java/de/bixilon/minosoft/render/GameWindow.java

@@ -76,6 +76,11 @@ public class GameWindow {
             glPopMatrix();
             glfwSwapBuffers(openGLWindow.getWindowId());
         }
+        // The window was closed, close everything
+        currentConnection.disconnect();
+        currentConnection = null;
+        running = false;
+        openGLWindow.close();
     }
 
     public static void pause() {

src/main/java/de/bixilon/minosoft/render/OpenGLWindow.java

@@ -49,6 +49,10 @@ public class OpenGLWindow {
         gluPerspective(fovY, width / (float) height, 0.1f, 500f);
     }
 
+    public void close() {
+        glfwDestroyWindow(windowId);
+    }
+
     public void init() {
         GLFWErrorCallback.createPrint(System.err).set();