ValueError: Buffer dtype mismatch, expected 'int_t' but got 'long long'

Hi, I'm getting the following error when running `testing.py`:

```python
random_forest = create_forest(train_data, n_trees=450, max_depth=15, max_x=3)
ValueError: Buffer dtype mismatch, expected 'int_t' but got 'long long'
ValueError: Buffer dtype mismatch, expected 'int_t' but got 'long long'
Exception ignored in: 'rf_cython.randomforest.gini_index'
```