[Lena-Richter]

Closes #2471

Describe your changes here:
This PR introduces an RBF-based mesh deformation, using OpenCASCADE and Eigen. It implements support for the compactly supported (CPC2) and globally supported (TPS) basis functions to compute the deformation for the inner nodes from the displacement of the boundary nodes. Additionally, for CPC2, a dynamic radius is implemented as well as a grading factor. The deformed geometry needs to have the same parametrization as the input geometry, otherwise the deformation will not work.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.35%. Comparing base (50f62c8) to head (6f20288).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2470      +/-   ##
==========================================
+ Coverage   83.05%   83.35%   +0.29%     
==========================================
  Files         148      147       -1     
  Lines       22259    22179      -80     
==========================================
  Hits        18488    18488              
+ Misses       3771     3691      -80     

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[ole-alb]

Thank you for this very cool contribution and implementation. I have a couple general remarks.
Can you check if ervything that can be const is const?

Please add tests for your functionality as it is not tested yet. Please also test the new dependecy on the newly added thirdparty library Eigen.
After the PR is merged, please keep in mind to update the wiki accordingly (Eigen, CMake,..).

Also I thought if there could be the option to use a system Eigen like it is for SC and p4est?

And last but not least, I coudn't find you in the CITATION.cff and in doc/auther_. Please add yourself here.

[ole-alb]

I only have a few small remarks. Also I stumble upon one thing. Why is CPC2 the default, when you'd always recommend TPS and the default radius if CPC2 isn't really applicable to general applications?

[ole-alb]

The build fails, because the file isn't remove from here. This also lead me to notice that the new CMake option is not enabled anywhere in the CI. So your CI ran through even though the build fails.

[ole-alb]

Suggested change

	given-names: Lena-René
	- given-names: Lena-René

[ole-alb]

Why did you remove Florians Orcid?

[sandro-elsweijer]

Heyho,
I needed this branch and it was not going to build. I fixed that and activated the CI for Eigen so that this code is also checked in the CI.
Furthermore, I had do move all code using Eigen in headers into source files. We have to keep all Eigen inlcudes only in source files since we link privately against Eigen.
This means, that only t8code sees Eigen, not the application linking against t8code. And when the application includes a t8code header file which includes Eigen, the application indirectly includes Eigen and is not able to find it and wont compile.
Make shure to pull before you work on this.
@Lena-Richter @ole-alb