Fixing Specific Hole

[tillns]

Hi! Currently, there's an option to fill only small holes, i.e., holes that have only a maximum number of boundary edges. It would be cool to have a more general option to specifically select a hole. A start would be to have a similar method to Basic_TMesh::fillSmallBoundaries() that would make the check grd == nbe instead of grd <= nbe. This would ensure that only those holes with a specific number of boundary edges are filled. To avoid any kind of ambiguities, an option to specify the indices of the boundary would be best.