Rename AppendModeOutputStreamResource to PrintableOutputStreamResource
Rename Path.<! and <<! to Path.!< and !<<
:white_check_mark: Check close of InputStream/OutputStream in test
:white_check_mark: Support char argument for Reader.FS/RS
:white_check_mark: Support char argument for Writer.OFS/ORS
:white_check_mark: Add a field value reader to Row