Among other issues, the Apple-supplied 0.9.7 libs for the 10.5 ABI cannot
verify newer SHA-256 certs as now used by python.org services. Document
in the installer ReadMe some of the certificate management issues that
users now need to be more concerned with due to PEP 476's enabling cert
verification by default. For now, continue to use the Apple-supplied
0.9.8 libs for the 10.6+ installer since they use Apple private APIs to
verify certificates using the system- and user-managed CA keychain stores.
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.
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.