changing IOError to OSError (#16715).

Thanks to Vajrasky Kok for the patch

test_imp.

to importlib.

Closes #11959: SMTPServer and SMTPChannel now take an optional map, use of which avoids affecting global state.

Fix bug in existing human test and add instructions; fix two bugs in tested
code; remove redundancies, add spaces, and change two internal method names.
Add mock_tk with mocks for tkinter.Variable subclasses and tkinter.messagebox.
Use mocks in test_config_name to unittest methods that are otherwise gui-free.

PEP accepted: http://mail.python.org/pipermail/python-dev/2013-June/126734.html

Cleanup also the code to follow the Python coding style (PEP 7).

The result type is int, return -1 to avoid a compiler warning (cast Py_ssize_t
to int).  PyObject_Size() can only fail with -1, and anyway a constructor
should return -1 on error, not an arbitrary negative number.

iterators: change the C type of tupleiterobject.it_index from long to
Py_ssize_t.

by their HANDLE which is a pointer (and not a long, which is smaller).

EOF is hit while trying to read the header of a bytecode file.

multiprocessing.h: remove unused MIN and MAX macros

change the C type of seqiterobject.it_index from long to Py_ssize_t.

encoding, and socket.gethostname() now decodes the hostname from the locale
encoding, instead of using the UTF-8 encoding in strict mode.

socket.gethostname() now decodes the hostname from the locale encoding, instead
of using the UTF-8 encoding in strict mode.