Quiet output of cv::error in Java tests

Introduced new Java API
void org.opencv.core.Core.setErrorVerbosity(boolean verbose)
used to suppress output to stderr from OpenCV's asserts

modules/java/generator/src/cpp/common.h

@@ -22,6 +22,10 @@
 
 #include "converters.h"
 
+#include "core_manual.hpp"
+#include "features2d_manual.hpp"
+
+
 #ifdef _MSC_VER
 #  pragma warning(disable:4800 4244)
 #endif

modules/java/generator/src/cpp/core_manual.cpp

@@ -0,0 +1,15 @@
+#define LOG_TAG "org.opencv.core.Core"
+#include "common.h"
+
+static int quietCallback( int, const char*, const char*, const char*, int, void* )
+{
+    return 0;
+}
+
+void cv::setErrorVerbosity(bool verbose)
+{
+    if(verbose)
+        cv::redirectError(0);
+    else
+        cv::redirectError((cv::ErrorCallback)quietCallback);
+}

modules/java/generator/src/cpp/core_manual.hpp

@@ -2,6 +2,13 @@
 
 #include "opencv2/core/core.hpp"
 
+namespace cv
+{
+
+CV_EXPORTS_W void setErrorVerbosity(bool verbose);
+
+}
+
 #if 0
 
 namespace cv