WriteStream are now subclasses of it.
* Added new methods eos(), ioFailed(), clearIOFailed() to
all streams. This allows better error checking.
* SaveFile classes take advantage of these new standard
stream APIS
* Removed File::gets()
* Added SeekableReadStream::readLine() (replaces File::gets)
* Added WriteStream::writeString, for convenience
svn-id: r17752