[Groff] Request "cf"

[Miklos Somogyi]

The 1.19.2 edition of groff documentation presents the trf and cf  
requests for
including files in diversions.
The trf request works well, but it does some processing of its input.
The cf request is supposed to do the same as trf except it would not  
process
its input in any way.

Unfortunately cf does not seem to do a thing.
Is it not implemented in 19.2?
Does it need a different treatment from trf?
Perhaps a flag needs to be set somewhere?

Miklos