Update documentation for csv module to reflect changes in code,
specifically that it now expects unicode input (and therefore the
paragraph about it not handling unicode is deleted, as well as
the 'how to handle unicode' examples) and that files should
be opened with "newline=''" instead of binary mode. Also removed
unused BytesIO import from test_csv.
This addresses issue 4847.
diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index c24c55f..7eb3a7f 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -6,7 +6,7 @@
import sys
import os
import unittest
-from io import StringIO, BytesIO
+from io import StringIO
from tempfile import TemporaryFile
import csv
import gc