[boost] [date_time] from_iso_string cannot read the output from to_iso_string

Hello, I use boost::posix_time::to_iso_string & boost::posix_time::from_iso_string to serialize/deserialize some dates. However, although to_iso_string handle spacial date values (ie -infinity), from_iso_string does no handle them, therefore, I have to test for those values myself. I think it would be better if the from_... and the to_... were exactly symetrical, and enabled a roundtrip. -- Loïc