[Swan-dev] rsasigkey --password

[D. Hugh Redelmeier]

The code treats a password of <configdir>/nsspassword as special: it 
signifies that the password should come from that file.

That was undocumented in rsasigkey(8), so I've fixed that.

But I think that this is very odd.  Probably a mistake.

- it uses inband signalling, really dumb in security contexts

- the signal is awkward to type and depends on knowing the <configdir>

Surely it would be better to have a different flag for this purpose.  
Perhaps --passwordfile.