Moved the exit on escape into Window, and added a virtual free method on both

Window an Viewer to clean up the windows, this is now called before exit is
finally called, ensure that more more memroy is clean up prior to exit.

src/osgGLUT/Window.cpp

@@ -33,6 +33,9 @@ Window::Window()
     _mx = _ww/2,
     _my = _wh/2;
     _mbutton = 0;    
+    
+    _exit = false;
+
 }
 
 
@@ -40,6 +43,9 @@ Window::~Window()
 {
 }
 
+void Window::clear()
+{
+}
 
 /**
   * Configure and open the GLUT window for this Window
@@ -82,6 +88,7 @@ bool Window::open()
 void Window::displayCB()
 {
     s_theWindow->display();
+    s_theWindow->check_if_exit();
 }
 
 
@@ -89,56 +96,66 @@ void Window::displayCB()
 void Window::reshapeCB(int w, int h)
 {
     s_theWindow->reshape(w, h);
+    s_theWindow->check_if_exit();
 }
 
 
 void Window::visibilityCB( int state )
 {
     s_theWindow->visibility(state);
+    s_theWindow->check_if_exit();
 }
 
 
 void Window::mouseCB(int button, int state, int x, int y)
 {
     s_theWindow->mouse(button, state, x, y);
+    s_theWindow->check_if_exit();
 }
 
 
 void Window::mouseMotionCB(int x, int y)
 {
     s_theWindow->mouseMotion(x,y);
+    s_theWindow->check_if_exit();
 }
 
 
 void Window::mousePassiveMotionCB(int x, int y)
 {
     s_theWindow->mousePassiveMotion(x,y);
+    s_theWindow->check_if_exit();
 }
 
 
 void Window::keyboardCB(unsigned char key, int x, int y)
 {
     s_theWindow->keyboard(key,x,y);
+    s_theWindow->check_if_exit();
 }
 
 void Window::specialCB(int key, int x, int y)
 {
     s_theWindow->special(key,x,y);
+    s_theWindow->check_if_exit();
 }
 
 void Window::spaceballMotionCB(int x, int y, int z)
 {
     s_theWindow->spaceballMotion(x,y,z);
+    s_theWindow->check_if_exit();
 }
 
 void Window::spaceballRotateCB(int x, int y, int z)
 {
     s_theWindow->spaceballRotate(x,y,z);
+    s_theWindow->check_if_exit();
 }
 
 void Window::spaceballButtonCB(int button, int state)
 {
     s_theWindow->spaceballButton(button,state);
+    s_theWindow->check_if_exit();
 }
 
 
@@ -236,3 +253,18 @@ bool Window::run()
 
     return true;
 }
+
+void Window::check_if_exit()
+{
+    if (_exit)
+    {
+        clear();
+    
+        #ifdef __MWERKS__
+        std::exit(0); // avoid collision of std::exit(..) / exit(..) compile errors.
+        #else
+        exit(0);
+        #endif
+    }
+}
+