Add class BaseNoise and GaussianNoise for the concept of exploration noise.
Add new test for sac tested in MountainCarContinuous-v0,
which should benefits from the two above new feature.
* Enable to convert Batch data back to torch.
* Add torch converter to collector.
* Fix
* Move to_numpy/to_torch convert in dedicated utils.py.
* Use to_numpy/to_torch to convert arrays.
* fix lint
* fix
* Add unit test to check Batch from/to numpy.
* Fix Batch over Batch.
Co-authored-by: Alexis Duburcq <alexis.duburcq@wandercraft.eu>
* add sum_tree.py
* add prioritized replay buffer
* del sum_tree.py
* fix some format issues
* fix weight_update bug
* simply replace replaybuffer in test_dqn without weight update
* weight default set to 1
* fix sampling bug when buffer is not full
* rename parameter
* fix formula error, add accuracy check
* add PrioritizedDQN test
* add test_pdqn.py
* add update_weight() doc
* add ref of prio dqn in readme.md and index.rst
* restore test_dqn.py, fix args of test_pdqn.py
