fix values of FTDecayFunctionVoigt 1D & 2D

1D: without the fix m_eta refers to the same as m_decay_length => calculations will be wrong
2D: without the fix m_eta refers to the same as m_decay_length_x => calculations will be wrong
2D: the ctor values have been in wrong order => clone will be wrongly initialized

@j.wuttke I found this on my way in the distribution/paramPool refactoring. Even if the refactoring is not working in the end, this fix should stay, therefore I made this extra MR

changed the description

Many thanks for spotting this. Most probably I broke it in 1.18, see CHANGELOG (1.18 API 6: Swap order of arguments).

Besides FTDecayFunction2DVoigt, we also have FTDistribution*DVoigt. Can you please check whether the same correction is needed over there.

And please add a line to CHANGELOG, since this fixes a severe bug and therefore needs to be documented.

added GUI bug labels

added 1 commit

• 55eb4a1b - add entry in changelog

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checked FTDistribution1DVoigt and FTDistribution2DVoigt, they are correct.

Added entry in changelog

approved this merge request

merged

mentioned in commit 1284f7fa