add support to export the bst surfaces as STL files.

[tmedani]

hi guys,

it seems STL is one of the most used and common format for the surfaces meshes.

currently, BST has these format:

This issue is just to remind the need to add the STL file format to the export function.

[chinmaychinara91]

Yes we can. That should be pretty doable very similar to the obj reader here in the PR 0d656e9

STL and PLY are both very widely used formats after OBJ.

[Edouard2laire]

This issue is just to remind the need to add the STL file format to the export function.

As a temporary workaround until Brainstorm can export directly STL file; it is possible to use freesurfer to convert gii file to STL using mris_convert

[rcassani]

To create .stl files from Brainstorm surfaces, I export them as either .off or .obj, then use MeshLab.