message: [move sift.cpp] sift: avoid inplace calls of GaussianBlur
  should unlock IPP optimizations
  original commit:
diff: @@ -209,14 +209,16 @@ static Mat createInitialImage( const Mat& img, bool doubleImageSize, float sigma
  #else
  resize(gray_fpt, dbl, Size(gray_fpt.cols*2, gray_fpt.rows*2), 0, 0, INTER_LINEAR);
  #endif
  - GaussianBlur(dbl, dbl, Size(), sig_diff, sig_diff);
  - return dbl;
  + Mat result;
  + GaussianBlur(dbl, result, Size(), sig_diff, sig_diff);
  + return result;
  }
  else
  {
  sig_diff = sqrtf( std::max(sigma * sigma - SIFT_INIT_SIGMA * SIFT_INIT_SIGMA, 0.01f) );
  - GaussianBlur(gray_fpt, gray_fpt, Size(), sig_diff, sig_diff);
  - return gray_fpt;
  + Mat result;
  + GaussianBlur(gray_fpt, result, Size(), sig_diff, sig_diff);
  + return result;
  }
  }
  