Add example for working with SRF and POI files

[ofgulban]

It would be useful to have an showing how to work with SRF (triangular mesh surface) and POI (patches of interest) files.

Example can be based on this dataset: https://search.kg.ebrains.eu/instances/Dataset/ff71a4d1-ea14-4ed6-898e-b92d95b3c446

*image from https://github.com/ofgulban/cortical-auditory-atlas .

[ofgulban]

Added an example script (with 68186d2 ), see: examples/read_srf_and_poi_export_obj.py script.

This script:

1. reads an SRF and a POI file (they need to have matching number of vertices).
2. Extracts the surface geometry from the SRF file.
3. Extract patch information from the POI file.
4. Exports these information into a wavefront obj file

Screenshots below are taken from BrainVoyager v 22.4.4 (left) and after the "SRF and POI to colored OBJ" conversion (taken from MeshLab v1.3.2, on the right)

Data used in this example is here:
example_data_SRF_POI.zip