TextFileReader read lines from a text file. It is aimed to be used by
all classes that read from a text file, as TextFileWriter is used by
those which write to a text file.
Code of TextFileReader is taken from class InputCSV.
Minor fixes on the TextFileWriter unit test.
TextFileWriter:
- OutputFileMedium becomes TextFileWriter.
- Method write_string_to_file() becomes write_text() and is made public.
- Add a unit test.
InputLogCSV and OutputCSV do not extend OutputFileMedium anymore, but
use a TextFileWriter as an attribute.