Converts the Steiner tree to smooth paths

## Arguments

- g
Steiner tree computed with tnss_tree

- bw
bandwidth of Gaussian Kernel

- n
number of extra nodes to include per edge

## Details

see see online for tips on plotting the result

## Examples

```
xy <- cbind(state.center$x,state.center$y)[!state.name%in%c("Alaska","Hawaii"),]
xy_dummy <- tnss_dummies(xy,root = 4)
gtree <- tnss_tree(cali2010,xy,xy_dummy,root = 4,gamma = 0.9)
#> This graph was created by an old(er) igraph version.
#> Call upgrade_graph() on it to use with the current igraph version
#> For now we convert it on the fly...
tree_smooth <- tnss_smooth(gtree,bw = 10,n = 10)
```