Dataset split incorrect in train_rig_approximation.py

[alexrogozea]

In train_rig_approximation.py the dataset split is done incorrectly, leading to the training dataset overlapping 80% with the validation dataset, both being 90% of the whole dataset.

Here:
dataset = ToyDataset(data['arr_0'][:-100], data['arr_1'][:-100])
validate_dataset = ToyDataset(data['arr_0'][100:], data['arr_1'][100:])