[WIP] Locality Sensitive Hashing for approximate nearest neighbor search(GSoC)

Please fix the rng used in the tests. Pass a fixed `random_state=0` value to the `LSHForest` instances and use:

```python
rng = np.random.RandomState(42)
for i in range(n_iter):
    n_neibors = rng.randint(0, samples)
    ...
```