use with statement to ensure zipfile is always closed (closes #20102)
Issue #19320: Fixed split/splitlist tests in test_tcl for Tcl 8.5.0-8.5.5.
Issue #20423: fix documentation of io.StringIO's newline parameter
Issue #19990: Install test/imghdrdata.
Issue #20435: Fix _pyio.StringIO.getvalue() to take into account newline translation settings.