* Fix support of batch over batch for Buffer.
* Do not use internal __dict__ attribute to store batch data since it breaks inheritance.
* Various fixes.
* Improve robustness of Batch/Buffer by avoiding direct attribute assignment. Buffer refactoring.
* Add axis optional argument to Batch stack method.
* Add item assignment to Batch class.
* Fix list support for Buffer.
* Convert list to np.array by default for efficiency.
* Add missing unit test for Batch. Fix unit tests.
* Batch item assignment is now robust to key order.
* Do not use getattr/setattr explicity for simplicity.
* More flexible __setitem__.
* Fixes
* Remove broacasting at Batch level since it is unreliable.
* Forbid item assignement for inconsistent batches.
* Implement broadcasting at Buffer level.
* Add more unit test for Batch item assignment.
Co-authored-by: Alexis Duburcq <alexis.duburcq@wandercraft.eu>