[<-.multiPhylo does not support empty []

[ms609]

The syntax myList[] <- X typically allows entries of a list to be modified without overwriting attributes.

Compare:

myList <- structure(1:5, class = 'myClass')
class(myList) # "myClass"

myList[] <- sapply(myList, `*`, 2)
class(myList) # attributes retained

myList <- lapply(myList, `*`, 2)
class(myList) # attributes lost

[ms609]

Accidental duplicate of #36, sorry!