Fix PCA demo and remove debug warnings

AABB_tree/demo/AABB_tree/MainWindow.cpp

@@ -45,6 +45,7 @@ MainWindow::MainWindow(QWidget* parent)
 
 MainWindow::~MainWindow()
 {
+  m_pViewer->makeCurrent();
   delete ui;
 }
 

GraphicsView/include/CGAL/Qt/qglviewer_impl.h

@@ -216,16 +216,6 @@ void CGAL::QGLViewer::initializeGL() {
          || QCoreApplication::arguments().contains(QStringLiteral("--old")))
 
     {
-      format.setDepthBufferSize(24);
-      format.setStencilBufferSize(8);
-      format.setVersion(2,0);
-      format.setRenderableType(QSurfaceFormat::OpenGLES);
-      format.setSamples(0);
-      format.setOption(QSurfaceFormat::DebugContext);
-      QSurfaceFormat::setDefaultFormat(format);
-
-      needNewContext();
-      qDebug()<<"GL 4.3 context initialization failed. ";
       is_ogl_4_3 = false;
     }
     else

Principal_component_analysis/demo/Principal_component_analysis/MainWindow.cpp

@@ -48,6 +48,7 @@ MainWindow::MainWindow(QWidget* parent)
 
 MainWindow::~MainWindow()
 {
+        m_pViewer->makeCurrent();
         delete ui;
 }
 

Principal_component_analysis/demo/Principal_component_analysis/Scene.cpp

@@ -28,6 +28,7 @@ Scene::Scene()
 
 Scene::~Scene()
 {
+
     delete m_pPolyhedron;
 }