#260 hfst-fst2strings uncaught exception when using option -N

[sjurum]

To repeat:

$ hfst-fst2strings -N 20 src/analyser-gt-desc.hfst 
libc++abi.dylib: terminating with uncaught exception of type FunctionNotImplementedException
Abort trap: 6

Expected behavior: an error message and a clean stop, or a working option :)

Hfst version: Svn trunk at revision 3984.

[Erik Axelson]

Optimized lookup format does not support option --nbest. Fixed in revision 3985 where an error mesage is printed.