message: Fix error in LineIterator example code in doc
diff: @@ -4819,7 +4819,7 @@ LineIterator it2 = it;
  vector<Vec3b> buf(it.count);
  for(int i = 0; i < it.count; i++, ++it)
  - buf[i] = *(const Vec3b)*it;
  + buf[i] = *(const Vec3b*)*it;
  // alternative way of iterating through the line
  for(int i = 0; i < it2.count; i++, ++it2)
  