Improved dataset

[YohannPerron]

This PR offers a unified interface for all dataset. It implement a version of the simulated dataset compatible with the new data format and a semi-measured dateset with projection of the original images to object plane.

Please also refer to the doc on contributing for more details.

• Have you run the tests by running pytest from the repository root? See the documentation for more details.
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• Is there a unit test for the proposed code modification? If the PR addresses an issue, the test should make sure the issue is fixed.
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• Did you document the proposed change(s) in the CHANGELOG file? It should go under "Unreleased".

Happy PR 😃