Add GeomAPI_PointsToBSpline as an optional alternative algorithm in CSTCurveBuilder

[joergbrech]

Fixes #1048

Description

This PR adds the option to set the algorithm in CCSTCurveBuilder. The current algorithm based on a Chebychev approximation creates relatively good curves with few control points, but it potentially introduces discontinuities in the curvature, because the approximation is performed segmentwise and the segments are concatenated without taking second derivatives into account.

With the changes introduced here, the CCSTCurveBuilder constructor gets a new optional enum argument, to switch the algorithm to OCCT's GeomAPI_PointsToBSpline implementation for the approximation. This results in a C3 continuous B-Spline of degree 4 which is much smoother, but may have more control points.

How Has This Been Tested?

The existing CSTApprox tests have been parametrized, such that the both algorithms are tested. In addition, the profile definition from the issue description in #1048 has been added. As it turns out, the old implementation fails to satisfy the prescribed tolerance of 1e-5 for this specific choice of CST parameters.

The image shows the curvature comb for the Chebychev approximation (default algorithm that was used thus far) to the right in the back and the curvature comb for the approximation based on GeomAPI_PointsToBSpline to the left/front.

Checklist:

Task	Finished	Reviewer Approved
At least one test for the new functionality was added.	yes does not apply	OK
New classes have been added to the Python interface.	yes does not apply	OK
The code is properly documented with doxygen docstrings	yes does not apply	OK
Changes are documented at the top of ChangeLog.md	yes does not apply	OK

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 69.50%. Comparing base (23808d7) to head (9b3964f).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
src/geometry/CCSTCurveBuilder.cpp	95.45%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1049      +/-   ##
==========================================
+ Coverage   69.48%   69.50%   +0.01%     
==========================================
  Files         301      301              
  Lines       26894    26912      +18     
==========================================
+ Hits        18688    18705      +17     
- Misses       8206     8207       +1     

Flag	Coverage Δ
unittests	69.50% <95.45%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/geometry/CCSTCurveBuilder.cpp	96.15% <95.45%> (-0.91%)	⬇️

[AntonReiswich]

I somehow can not tick the boxes in the checklist? ( In the Reviewer approved column)
Is it supposed to be like this?

[joergbrech]

I somehow can not tick the boxes in the checklist? ( In the Reviewer approved column)
Is it supposed to be like this?

Yeah, it doesn't work. You have to edit the PR message and modify the raw markdown. Unfortunately GH does not support checklists in tables very well.

[AntonReiswich]

I see. Ok, that also works. done.