Tensor update issue

I noticed in a lot of place, the output Tensor is updated by creating a new Tensor and setting as the operator output. This is really computationnally heavy:

    // set the attributes

    clipOp->max() = max;
    clipOp->min() = min;

    // Retrieve the previous min/max tensors

    auto minTensor = std::static_pointer_cast<OperatorTensor>(clipNode->getOperator())->getInput(1);
    auto maxTensor = std::static_pointer_cast<OperatorTensor>(clipNode->getOperator())->getInput(2);

    // Create the new min/max tensors

    std::shared_ptr<Tensor> newMinTensor = std::make_shared<Tensor>(min);
    newMinTensor->toBackend(minTensor->backend());
    newMinTensor->toDformat(minTensor->dformat());
    newMinTensor->toDtype(minTensor->dtype());

    std::shared_ptr<Tensor> newMaxTensor = std::make_shared<Tensor>(max);
    newMaxTensor->toBackend(maxTensor->backend());
    newMaxTensor->toDformat(maxTensor->dformat());
    newMaxTensor->toDtype(maxTensor->dtype());

    // Set the tensors of the producer

    auto minProducer = clipNode->getParent(1);
    minProducer->getOperator()->setOutput(0, newMinTensor);

    auto maxProducer = clipNode->getParent(2);
    maxProducer->getOperator()->setOutput(0, newMaxTensor);

Instead, you can simply update the Tensor has follow:

    auto minTensor = std::static_pointer_cast<OperatorTensor>(clipNode->getOperator())->getInput(1);
    auto maxTensor = std::static_pointer_cast<OperatorTensor>(clipNode->getOperator())->getInput(2);
    minTensor->copyCastFrom(std::make_shared<Tensor>(min));
    maxTensor->copyCastFrom(std::make_shared<Tensor>(max))

I started to update some functions in !67 (merged) but I let you do the other changes :)