Pull latest changes from FP recastnavigation fork
Among upstream recast changes this also includes a change to:
Bump RC_SPAN_HEIGHT_BITS from 13 to 16
Increasing the bits used, will yield more accurate height information in the generated navmesh voxels & polys.
This does not change the size of rcSpan on x64 platforms. (See https://godbolt.org/z/4eKq45daK)
Therefore, this is free accuracy improvement without perf or memory impact.