Bug in calcHist when accumulate flag is set to true (Feature #526)

When the accumulate flag is set to true, cvCalcHist crashes in the second call. I had this bug with opencv 2.1 but the problem still exists in svn trunk. I tracked the problem until this function (line 754 in trunk/opencv/modules/imgproc/src/histogram.cpp) :

static void calcHist( const Mat* images, int nimages, const int* channels,
                          const Mat& mask, [[SparseMat]]& hist, int dims, const int* histSize,
                          const float** ranges, bool uniform, bool accumulate, bool keepInt )

A SparseMatIterator iterator 'it' is used without initialization :

        [[SparseMatIterator]] it;
        size_t i, N;

        if( !accumulate )
            hist.create(dims, histSize, CV_32F);
        else
            for( i = 0, N = hist.nzcount(); i < N; i++, ++it )
            {
                int* value = (int*)it.ptr;
                *value = cvRound(*(const float*)value);
            }

To solve the problem, 'it' should be initialized to hist.begin().

            for( i = 0, N = hist.nzcount(), it = hist.begin(); i < N; i++, ++it )