…nGH-151579) (pythonGH-151650)

Replace the previously sparse reference documentation with full coverage of
the public API of the tkinter package, written from the Tcl/Tk manual pages,
the existing documentation and the module docstrings.

* Doc/library/tkinter.rst gains a "Reference" section documenting every public
  class, method, function and constant of the core module -- the widgets, the
  Misc, Wm, Pack, Place, Grid, XView and YView mix-ins, the Variable and image
  classes, the module-level functions and the symbolic constants.
* Doc/library/tkinter.ttk.rst, dialog.rst, tkinter.font.rst and the other
  module pages document their remaining classes, methods and functions.

The descriptions are Python-oriented (correct return types -- tuples rather
than Tcl lists, booleans, integers, None on cancellation, and so on) and were
checked against the Tcl/Tk 9.1 manual pages and the implementation.

versionadded, versionchanged and deprecated directives are added for the
public API, determined from the git history relative to Python 3.0: the
tkinter.ttk module (3.1); the Text, Wm, Menu and Misc methods exposing Tk 8.5
features (3.3); and the many later additions and behavior changes up to 3.15.
The Tk version required by features added after Tk 8.6 is noted as well.  The
bundled Tcl/Tk version is updated to 9.0 and the manual-page links point at
the tcl9.0 reference.

--------
(cherry picked from commit 8b270b7)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

* pythongh-86726: Adjust tkinter docs for the 3.14 backport

Remove documentation of API added only in 3.15 (the grid_content/
pack_content/place_content aliases, Text.search_all, the search
nolinestop/strictlimits parameters and Event.user_data/detail), date the
wm_attributes positional-argument deprecation to 3.13, and update the
bundled Tcl/Tk version to 8.6.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------
(cherry picked from commit 1141d29)

Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>