Find the mesh vertices where the distance to the opposite side is within a given range.

Input parameters:

1. Ms → Mesh to measure.
2. Rn → Thickness range for outputs. Measurements outside of this range will be omitted.
3. An → Angle at which a mesh feature is considered 'sharp'.
4. Gr → Optional gradient for point colouring.

Output parameters:

1. Vt → Vertex indices where the mesh thickness is within the given range.
2. Th → Thickness at each vertex index.
3. Pt → Points where the mesh thickness is within the given range.