Merge remote-tracking branch 'origin/2.4' into merge-2.4

Conflicts:
	modules/core/src/gl_core_3_1.cpp
	modules/core/src/opencl/convert.cl
	modules/cudaimgproc/src/cuda/canny.cu
	modules/cudastereo/perf/perf_stereo.cpp
	modules/gpu/perf/perf_imgproc.cpp
	modules/gpu/test/test_denoising.cpp
	modules/ocl/src/opencl/imgproc_resize.cl
	samples/cpp/Qt_sample/main.cpp

samples/android/native-activity/src/org/opencv/samples/NativeActivity/CvNativeActivity.java

@@ -21,6 +21,7 @@ public class CvNativeActivity extends Activity {
                     System.loadLibrary("native_activity");
                     Intent intent = new Intent(CvNativeActivity.this, android.app.NativeActivity.class);
                     CvNativeActivity.this.startActivity(intent);
+                    CvNativeActivity.this.finish();
                 } break;
                 default:
                 {
@@ -34,7 +35,7 @@ public class CvNativeActivity extends Activity {
         Log.i(TAG, "Instantiated new " + this.getClass());
     }
 
-   @Override
+    @Override
     public void onResume()
     {
         super.onResume();