Issue #19286: Adding test demonstrating the failure when a directory is found in the package_data globs.

loaded from .py[co] files.

Issue #19455: Corrected inaccuracies in documentation and corrected some incorrect cross-references.

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

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

screen refresh problem.

screen refresh problem.

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.