Motif of length < #residues will generate memory overflow, but not compilation error or crash

[blinard-BIOINFO]

If input motif matrix has a number of positions < to #nucleotides (4 only in current implementation), there is a memory overflow.
Funnily, this doesn't avoid to do pvalue computations without any crash.
However, when activating sanitizer, it is clearly raised.

// Matrix.h

void Matrix::computesIntegerMatrix (double granularity, bool sortColumns) {

   // [...] 
  matInt = new long long *[length];
  for (int k = 0; k < 4; k++ ) {
    matInt[k] = new long long[length];          //   << == overflow, as k will be > length
    std::cout << "test" <<  std::endl;
    for (int p = 0 ; p < length; p++) {
      matInt[k][p] = ROUND_TO_INT((double)(mat[k][p]*this->granularity)); 
    }
  }
  // [...]
}

This will need fix for any future version that will allow amino acids motifs or any generic alphabet.