gaouizer

#3191 Phase and Ratio Tap Changer transfortmer OM Models introduction…

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… with examples and nrts **Checklist before requesting a review** *use `'[x]'` to check the checkboxes, or submit the PR and then click the checkboxes* - [x] unit tests and...

**Checklist before requesting a review** *use `'[x]'` to check the checkboxes, or submit the PR and then click the checkboxes* - [ ] unit tests and non-regression tests were added...

3358 use iidm v 1 5 1

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**Checklist before requesting a review** *use `'[x]'` to check the checkboxes, or submit the PR and then click the checkboxes* - [ ] unit tests and non-regression tests were added...

[iidm4cpp v1.5.1](https://github.com/powsybl/powsybl-iidm4cpp/releases/tag/v1.5.1) is now available :warning: this needs an update on platforms side too!

BaseTapChangerPhaseShifterInterval takes a wrong tap.value when transiting to "Standard" state in some configurations

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When transiting to "Standard" state from a "Move*" state, BaseTapChangerPhaseShifterInterval imposes tap.value = pre(tap.value) whereas it might have imposed tap.value = pre(tap.value) + or - 1 at the same instant...

When creating an empty network, the sourceFormat attribute is empty whereas its use is required

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### Describe the current behavior when creating a network via the `network.create_empty()` function, the created network has an empty sourceFormat attribute and it does not seem that a setter is...

**Checklist before requesting a review** *use `'[x]'` to check the checkboxes, or submit the PR and then click the checkboxes* - [x] unit tests and non-regression tests were added (new...

**Checklist before requesting a review** *use `'[x]'` to check the checkboxes, or submit the PR and then click the checkboxes* - [ ] unit tests and non-regression tests were added...

In cpp transformer models, when associated with a tap changer, when tap changer's index changes the `dxy_dUlk_` member variable isn't updated concomitantly with the bus voltage resulting in erroneous current...