Bug in calibration.cpp sample

This was crashing my code:
    for( size_t i = 1; i < imagePoints.size(); i++ )
        objectPoints.push_back(objectPoints[0]);

Changed by:
objectPoints.resize(imagePoints.size(),objectPoints[0]);

Plus clean up on Qt code

samples/cpp/calibration.cpp

@@ -86,8 +86,8 @@ static bool runCalibration( vector<vector<Point2f> > imagePoints,
     
     vector<vector<Point3f> > objectPoints(1);
     calcChessboardCorners(boardSize, squareSize, objectPoints[0]);
-    for( size_t i = 1; i < imagePoints.size(); i++ )
-        objectPoints.push_back(objectPoints[0]);
+
+	objectPoints.resize(imagePoints.size(),objectPoints[0]);
     
     calibrateCamera(objectPoints, imagePoints, imageSize, cameraMatrix,
                     distCoeffs, rvecs, tvecs, flags);