Update to Forbild format and to new documentation

[axel-grc]

Pull Request Summary

Transition to Forbild Format

• Removed GeometricFileReader to fully adopt the forbild format.
• Modified tools:
  • rtkdrawgeometricphantom
  • rtkprojectgeometricphantom
• Removed rtkGeometricPhantomFileReader.
• Updated tests:
  • rtkdrawgeometricphantomtest
  • rtkprojectgeometricphantomtest
    Tests now exclusively read the forbild format.

Documentation

• Added the following documentation files:
  • CodeContribution.md
  • Geometry.md
  • Tutorial.md
  • CustomPhantom.sh
• Added new forbild files:
  • Geometries_forbild.txt.sha512
  • SheppLogan_forbild.txt.sha512
• Added new examples:
  • ForwardProjection
  • RayBoxIntersection
  • WaterPreCorrection
  • ConjugateGradient
• Removed rtkThreeDCircularProjectionGeometry.dox from Doxygen to integrate it into Sphinx.

To Do

• Convert phantom files in examples to the forbild format.
• Update the phantom text file and baseline objects to ensure identical results and pass tests.
• Complete the remaining examples.
• Verify and replace references to Doxygen Geometry documentation with links to the Sphinx Geometry documentation.
• Modernize the code for WaterPreCorrection.
• Add result images to the examples.
• Include the Image Quality section in the new documentation.
• Integrate the FanBeam 2D example from the old documentation into the ConjugateGradient example.