CMake Refactor

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This Pull Request modernizes CMake (resolves #56):

• Use CPM / PackageProject

• Update Include Structure

  • Don't artificially flatten
  • Use q-char-sequences where appropriate

• Copy required shared libraries when required / Setup proper path automatically when required

• Modernize Python Bindings (integration with gdsfactory and other open source python based EDA tools #65)

  • Use scikit-build-core
  • Re-use the shared libraries contained in the VTK-Python package
    • On Linux (using RPATH) [✅ Tested]
    • On MacOS (using RPATH) [✅ Tested]
    • On Windows (os.add_dll_directory) [⏳ Via viennaps.libs folder, awaiting upstream changes]

• Add library switch to ease location of installed dependencies (ViennaLS, ViennaRay, ...)

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Note to self: I still have to adjust the workflows and the app

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@tobre1 Was this some sort of merge conflict on your side?

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I've evaluated some possible solutions but most are way too hacky to be deemed viable - I have thus raised an issue on VTKs side: https://gitlab.kitware.com/vtk/vtk/-/issues/19279.

For now I'm going to add a viennaps.libs folder on those targets that require it (currently only windows) and copy the VTK libraries there for the time being.

[Curve]

The VTK libraries are now installed in the viennaps.libs folder only on windows for the time being - In case the VTK issue is resolved we could remove the libs folder on windows as well :)

[tobre1]

When building the examples, the binaries are now placed in build/examples-bin/. This change should also be addressed in the README Basic Examples - Building section.

[tobre1]

When local ViennaLS/ViennaRay packages are used (specified in VIENNAPS_LOOKUP_DIRS), OpenMP is not added to the dependencies when building the examples. I get the following error:

[cmake] CMake Error at examples/GDSReader/CMakeLists.txt:3 (add_executable):
[cmake]   Target "GDSReader" links to target "OpenMP::OpenMP_CXX" but the target was
[cmake]   not found.  Perhaps a find_package() call is missing for an IMPORTED
[cmake]   target, or an ALIAS target is missing?

[Curve]

When building the examples, the binaries are now placed in build/examples-bin/. This change should also be addressed in the README Basic Examples - Building section.

When local ViennaLS/ViennaRay packages are used (specified in VIENNAPS_LOOKUP_DIRS), OpenMP is not added to the dependencies when building the examples. I get the following error:

[cmake] CMake Error at examples/GDSReader/CMakeLists.txt:3 (add_executable):
[cmake]   Target "GDSReader" links to target "OpenMP::OpenMP_CXX" but the target was
[cmake]   not found.  Perhaps a find_package() call is missing for an IMPORTED
[cmake]   target, or an ALIAS target is missing?

Thanks for the thorough testing!

I've updated the README and pushed a fix for ViennaRay (regarding OpenMP) here: ViennaTools/ViennaRay#48

Please try to install ViennaRay locally again with commit 6f2d980

[Curve]

I've evaluated some possible solutions but most are way too hacky to be deemed viable - I have thus raised an issue on VTKs side: https://gitlab.kitware.com/vtk/vtk/-/issues/19279.

For now I'm going to add a viennaps.libs folder on those targets that require it (currently only windows) and copy the VTK libraries there for the time being.

VTK is working on a new way to make this possible, however it all seems to be highly work in progress right now