solution.

Currently, Tix is not built in Debug configuration.

This change also:
- simplifies some Tcl/Tk-related msbuild properties for _tkinter
- copies the Tcl and Tk DLLs into the build output directory, meaning
  they will always be available after a build without having to copy
  them manually or change PATH
- removes PCbuild/build_tkinter.py: the solution does the build without
  needing to invoke Python (so Tcl/Tk/Tix can be built in parallel with
  the rest of the build using the `/m` msbuild command line switch)
- removes an outdated README concerning building Tcl/Tk on AMD64

Closes #20995 by Enabling better security by prioritizing ciphers
such that:

* Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE)
* Prefer ECDHE over DHE for better performance
* Prefer any AES-GCM over any AES-CBC for better performance and security
* Then Use HIGH cipher suites as a fallback
* Then Use 3DES as fallback which is secure but slow
* Finally use RC4 as a fallback which is problematic but needed for
  compatibility some times.
* Disable NULL authentication, NULL encryption, and MD5 MACs for security
  reasons

Popa.

Patch by Claudiu Popa.

defined.

Issue19995: more informative error message; spelling corrections; use operator.mod instead of __mod__

loop in debug mode. Raise a RuntimeError if the event loop of the current
thread is different.  The check should help to debug thread-safetly issue.
Patch written by David Foster.

Instead we'll just use the stdlib zipfile module.  Patch by Derek Chiang

"equivalant" was caught by Tobias Käs on docs@, "seperated" and "chartruese"
were discovered by a spell-checker.

Pointed out by Colin Davis on docs@.

Issue #10141: updated new usages of AF_CAN to be in #ifdef AF_CAN rather than #ifdef HAVE_LINUX_CAN_H to allow compilation on older Linuxes.