Add visitor mechanism to triangulate hole() for progress feedback and cancellation

Add visitor mechanism to triangulate hole() for progress feedback and cancellation: a task in LegoFlow-SWE (Harbor dataset). The hole‑filling function triangulate hole() in the Polygon Mesh Processing package can take O(n³) time for a hole with n vertices. Currently there is no built‑in way for an…

The task

The hole‑filling function `triangulate_hole()` in the Polygon Mesh Processing package can take **O(n³)** time for a hole with *n* vertices. Currently there is no built‑in way for an application to monitor the algorithm’s progress, or to cancel an operation that is taking too long – for example when processing…

Part of Lego-X/LegoFlow-SWE.