Some third-party projects, such as matplotlib and PIL/Pillow,
depended on being able to build with Tcl and Tk frameworks in
/Library/Frameworks.  They were unable to build with the built-in
Tcl/Tk and/or execute correctly.

screen refresh problem.

It is causing trouble like e.g. hanging processes.

Make it easier for users to make use of the backup _tkinter linked
with the third-party Tcl and Tk frameworks in /Library/Frameworks.
The two tkinter variants are now installed in separate directories
under a new lib-tkinter.  This allows per-user selection by
manipulating sys.path, directly or with PYTHONPATH.  If this
proves useful, we can supply a more convenient user interface
to supply the paths.  For now, this remains somewhat experimental.

10.8+ when using a universal Python that included a PPC architecture,
such as with a python.org 32-bit-only binary installer.

of OPT for special build options.  By setting OPT, some compiler-specific
options like -fwrapv were overridden and thus not used, which could result
in broken interpreters when building with clang.

64-bit/32-bit installer for 10.6+.  It is no longer necessary
to install a third-party version of Tcl/Tk 8.5 to work around the
problems in the Apple-supplied Tcl/Tk 8.5 shipped in OS X 10.6
and later releases.

when building _tkinter.  configure has two new options; if used, both must
be specified:

  ./configure \
      --with-tcltk-includes="-I/opt/local/include" \
      --with-tcltk-libs="-L/opt/local/lib -ltcl8.5 -ltk8.5"

In addition, the options can be overridden with make:

   make \
       TCLTK_INCLUDES="-I/opt/local/include" \
       TCLTK_LIBS="-L/opt/local/lib -ltcl8.6 -ltk8.6"

Issue #19352: Fix unittest discovery when a module can be reached through several paths (e.g. under Debian/Ubuntu with virtualenv).

Issue #15207: Fix mimetypes to read from correct area in Windows registry (Original patch by Dave Chambers)

Python executable and not removed by the linker's optimizer.

limiting the call to readline().  Original patch by Michał
Jastrzębski and Giampaolo Rodola.

Skip tests for 24-bit wave file on big-endian platforms.