This reuses existing code to hopefully make the new test_input_no_stdout_
fileno() test work. It is hanging Free BSD 9 and OS X Tiger buildbots, and I
don't know why.

Also add to comment in the C code.

Also factored out some test cases into a new PtyTests class.

sys.path has an unwritable __pycache__ directory.

This typically comes up when someone runs the test suite from an
administrative install of Python on Windows where the user does not
have write permissions to the stdlib's directory.

Thanks to Zachary Ware and Matthias Klose for reporting bugs related
to this issue.

This is a relatively benign bug, since having both be true was correctly
rejected at in SMTPServer even before this patch.

Patch by Xiang Zhang.

Patch by Henrik Heimbuerger and Bar Harel.

Patch by Henrik Heimbuerger and Bar Harel.

Also change glossary heading from view