shutil.rmtree() in tearDown().  add missing tests to the list
in the test_bsddb3 suite.

I really want to test the buildbots.  This change is necessary
to get the test to be more stable and not crash due to previous
processes exitting.

 1) tempfile.TemporaryFile, NamedTemporaryFile, and SpooledTemporaryFile
    now pass newline and encoding to the underlying io.open call.
 2) test_tempfile is updated
 3) test_csv is updated to use the new arguments.

to be a text file.  (XXX It should use UTF-8 as the encoding.)
I also removed the unised 'binary' argument from the make_file() signature.

XXX I am under no illusion that this is now working; I're pretty sure
it would be more principled if it always read binary data.  But that's
for someone who actually cares about this module.

Moved fieldnameiterator and formatteriterator to stringlib/string_format.h, so that they can be used when backporting to 2.6.

(XXX Though perhaps temp files should be created in text mode by default?!)

Cleanup in anticipation of moving formatteriterator and fieldnameiterator into stringlib/string_format.h.

see a better way; the 'Binary' class is poorly specified so it's unclear
what behavior is relied upon.

(And if there are, they will now get an error when used.  So fix them!)

- Replace all asserts by ValuleErrors or TypeErrors as appropriate.
- Add _checkReadable, _checkWritable methods; these check self.closed too.
- Add a test that everything exported by io.py exists, and is either
  an exception or an IOBase instance (except for the open function).
- Default buffering to 1 if isatty() (I had to tweak this to enforce
  the *default* bit -- GvR).