Allows removing areas of a navmesh defined by scene-placed AABB-nodes (also provided by the addon). Only removes whole polygons whose points fall inside the AABB, does not clip them to their precise bounds (for now?) - see screenshot
Mainly useful to remove unused floating islands that tend to almost always be generated when baking heightmaps.
Quick How to: Add 'AABBNode's as children of a NavMeshInstance and select the NavMeshInstance. Next to the Bake button in the menu-bar a 'Clip' button will appear. Clicking it will process any existing baked navmesh, so the order is Bake->Clip
