You might want to review this change as it's my first time.  Be gentle. :-)

ascii seems like the safest bet that it will exist.  I wonder if utf-8
would be a better choice?  This should get test_fileinput passing on OpenBSD.

implicit assumptions that there's no difference
between text and binary modes.

be used to control how files are opened.

specifying the file mode input files should be opened with.

current file number.

imports e.g. test_support must do so using an absolute package name
such as "import test.test_support" or "from test import test_support".

This also updates the README in Lib/test, and gets rid of the
duplicate data dirctory in Lib/test/data (replaced by
Lib/email/test/data).

Now Tim and Jack can have at it. :)

New test_fileinput.py from Nick Mathewson, fiddled to use TESTFN and sundry
style nits.