Closes #20218: Added convenience methods read_text/write_text and read_bytes/
write_bytes to pathlib.Path objects.

Thanks to Christopher Welborn and Ram Rachum for original patches.
Make pydoctheme compatible with Sphinx 1.3 HTML output changes.
merge with 3.4
Remove old overridden version of a Sphinx CSS file.

All Python-specific styling is now in the theme anyway.
merge with 3.4
Issue 22492: Be explicit that print does not support binary mode files.
Original patch by Georg Brandl.
Merge with 3.4