Nature plug-in update. Functionality of Landmass ability extended.
1.) HeightFieldMesh now contains working implementation of ComputeAltitudeAt() and ComputeIntersectionWithRay().
See documentation in LandMesh.h and example usage in LandAbility.cpp (commented code at the end of LoadTerrainBlocks() method).
NOTE: Current version of ComputeIntersectionWithRay() only computes APPROXIMATE intersection.