The attached patch will dump a correct TNEF in a X.420
FileTransferData (like before), but I don't have time to dig deeper
into this to determine if this is an appropriate solution. Maybe
the X.420 dissector should decode the actx->external.octet_aligned
data for each bodypart and put them in a top tree node?
Or even better a patch like this to dump as octet-string when unknown