A terraforming/smoothing command for minetest-WorldEdit
//terraform <radius> <threshold> <shape>
radius: Radius of the terraform operation (0 to radius_limit).
threshold: Threshold value for the operation (0 to 100).
shape: Shape of the terraform area, either "sphere" or "cube".
radius_limit: Maximum allowable radius for the terraform operation.
threshold_multiplier: Multiplier applied to the threshold value.
gauss_sigma: The sigma value used in the generation of the guassian kernel.
guass_radius: The radius of the kernel.
//terraform 10 100 sphere
//terraform 5 30 cube
//brush terraform 7 0 sphere