`fold` doesn't carry over name

[rajarshi]

When folding a fingerprint that has the name and source fields set, these fields are unset in the resultant fingerprint

> fp <- new("fingerprint", nbit=64, bits=sample(1:64, 30), name='foo')
> fp@name
[1] "foo"
> fold(fp)
Fingerprint object
 name =   
 length =  32 
 folded =  TRUE 
 source =  R 
 bits on =  1 2 5 6 8 9 10 12 13 14 16 17 19 20 21 22 24 25 26 27 28 30 31