[SOFA] Creation of new componeent responsible on translating the skeleton txt file into a vtk one

[bouamarakamelia]

1. Description

Adds a new SkeletonReader component to MeshSkeletonizationPlugin.
It reads the polyline skeleton file produced by MeshSkeletonization and rebuilds it in memory as a proper node graph
(id, parents, children, mesh correspondence), rooted as a tree from a chosen entry point, and exportable as .vtk for visualization in ParaView.

2. New features according to the 3 main classes

SkeletonNode : skeleton point as a data class

Plain C++ class (no SOFA/CGAL dependency).
Stores id, 3D position, parentIds/childrenIds, and optional mesh-correspondence fields (meshVertexId, distanceToMesh).

SkeletonGraph : parsing + tree building

• loadFromFile(): parses the polyline text format, merges coincident points into one node.
• buildTree(): BFS from an entry point, fills parent/child ids, flags loop/anastomosis (when veins loop over each other) edges instead of dropping or duplicating them.
• computeMeshCorrespondence(): links each node to its closest mesh vertex.
• exportToVTK(): writes points, tree-edge lines, and type/depth/is_loop scalars.

SkeletonReader : SOFA DataEngine wrapper

Exposes the above as scene Data fields (filename, inputVertices, entryPoint in; outputVTK, nodeCount out).
Registered in init.cpp alongside MeshSkeletonization.
init() forces one update() pass so it also runs correctly in batch mode, not just when a GUI happens to read its outputs.

3. Results

A comparison window between the txt file output on SOFA and the vtk file output dependent from MeshSkeletonization plugin on the left opened in 3DSlicer.