FIXED code cleaning (C++11)

sdk/applications/imp/ImpMainWindow.cpp

@@ -136,15 +136,15 @@ void ImpMainWindow::setCentralViewer(Viewer* theViewer) {
 // ------------- initActions -----------------
 void ImpMainWindow::initActions() {
     //-- Check for action applications
-    ActionExtension* applicationActionExtension = NULL;
+    ActionExtension* applicationActionExtension = nullptr;
     QListIterator<ActionExtension*> it(ExtensionManager::getActionExtensionsList());
-    while (it.hasNext() && applicationActionExtension == NULL) {
+    while (it.hasNext() && applicationActionExtension == nullptr) {
         ActionExtension* current = it.next();
         if (current->getName() == "Application Level Actions") {
             applicationActionExtension = current;
         }
     }
-    if (applicationActionExtension == NULL) {
+    if (applicationActionExtension == nullptr) {
         CAMITK_ERROR(tr("Application error: the \"Application Level Actions\" extension is required by this application but could not be found\nIn any of the following extension directories:\n - %1\nPlease check your CamiTK configuration and/or installation using \"camitk-config --config\"").arg(Core::getActionDirectories().join("\n - ")))
         exit(EXIT_FAILURE);
     }