--- Applies changes to a heightmap to a Voxel Manipulator data block.
-- @param pos1 vector Position 1 of the defined region
-- @param pos2 vector Position 2 of the defined region
-- @param area VoxelArea The VoxelArea object (see worldedit.manip_helpers.init)
-- @param data number[] The node ids data array containing the slice of the Minetest world extracted using the Voxel Manipulator.
-- @param heightmap_old number[] The original heightmap from worldeditadditions.make_heightmap.
-- @param heightmap_new number[] The new heightmap containing the altered updated values. It is expected that worldeditadditions.table.shallowcopy be used to make a COPY of the data worldeditadditions.make_heightmap for this purpose. Both heightmap_old AND heightmap_new are REQUIRED in order for this function to work.
-- @param heightmap_size vector The x / z size of the heightmap. Any y value set in the vector is ignored.
-- @returns bool, string|{ added: number, removed: number } A bool indicating whether the operation was successful or not, followed by either an error message as a string (if it was not successful) or a table of statistics (if it was successful).