The type of the first (and now only) argument to the constructors called by
readFrom(istream&) has been changed from an istream& to an
OIOin&. This avoids naming conflicts with other constructors. Also,
OIOin is an abstract base class, and all input operators are virtual
functions, so you can customize the Object I/O format by defining your own
derived classes. OIOistream and OIOnihin implement a format
similar to the old OOPS format.