Rotates a dendrogram based on its seriation

The function tries to turn the dend into hclust using DendSer.dendrogram (based on DendSer)

Also, if a distance matrix is missing, it will try to use the cophenetic distance.

`rotate_DendSer(dend, ser_weight, ...)`

- dend
An object of class dendrogram

- ser_weight
Used by cost function to evaluate ordering. For cost=costLS, this is a vector of object weights. Otherwise is a dist or symmetric matrix. passed to DendSer.dendrogram and from there to DendSer.

If it is missing, the cophenetic distance is used instead.

- ...
parameters passed to DendSer

Numeric vector giving an optimal dendrogram order

`DendSer`

, DendSer.dendrogram ,
untangle_DendSer, rotate_DendSer

```
if (FALSE) {
library(DendSer) # already used from within the function
dend <- USArrests[1:4, ] %>%
dist() %>%
hclust("ave") %>%
as.dendrogram()
DendSer.dendrogram(dend)
tanglegram(dend, rotate_DendSer(dend))
}
```