To make sure RecastMesh objects are equal if built with the same data but in
different order. Will be used later when there will be more than one place
building RecasMesh objects.
To reduce cache size and make it more flexible.
Adding off mesh connections to the navmesh is the last step of navmesh
generation and it's very fast comparing to other steps (microseconds vs
milliseconds). Having less cache size makes get and set operations almost 2x
times faster that also have an order of microseconds. So in total there is
no performance impact.
This AABB tree required when need to filter out input mesh that has not
influence navmesh tile output. This filtering is already done before. Each
recast mesh corresponds to a single navmesh tile and has appropriate bounds.