* :ghpull:`19140`: Fix the docstring of suptitle/subxlabel/supylabel.

* :ghpull:`19132`: Normalize docstring interpolation label for kwdoc() property lists

* :ghpull:`19134`: Switch internal API function calls from cbook to _api

* :ghpull:`19125`: DOC: contributor incubator

* :ghpull:`18948`: DOC: Fix latexpdf build

* :ghpull:`18753`: Remove several more deprecations

* :ghpull:`18674`: Remove accidentally added swapfile.

* :ghpull:`18673`: Small cleanups to parasite axes.

* :ghpull:`18536`: axes3d panning

* :ghpull:`18672`: Created Border for color examples

* :ghpull:`18661`: Define GridFinder.{,inv\_}transform_xy as normal methods.

* :ghpull:`18656`: Fix some missing references.

* :ghpull:`18577`: Random test cleanups

* :ghpull:`18578`: Merge all axisartist axis_direction demos together.

* :ghpull:`18588`: Use get_x/yaxis_transform more.

* :ghpull:`18564`: Prepare for merging SubplotBase into AxesBase.

* :ghpull:`15127`: ENH/API: improvements to register_cmap

* :ghpull:`18576`: DOC: prefer colormap over color map

* :ghpull:`18251`: Merge v3.3.x into master

* :ghpull:`18329`: Change default keymap in toolmanager example.

* :ghpull:`18330`: Dedent rst list.

* :ghpull:`18320`: Make Colorbar outline into a Spine.

* :ghpull:`18316`: Safely import pyplot if a GUI framework is already running.

* :ghpull:`18321`: Capture output of CallbackRegistry exception test.

* :ghpull:`18226`: Use CallbackRegistry in Widgets and some related cleanup

* :ghpull:`18203`: Force locator and formatter inheritence

* :ghpull:`18279`: boxplot: Add conf_intervals reference to notch docs.

* :ghpull:`18261`: Migrate tk backend tests into subprocesses

* :ghpull:`17961`: DOCS: Remove How-to: Contributing

* :ghpull:`18201`: Remove mpl.colors deprecations for 3.4

* :ghpull:`18062`: Bump matplotlib.patches coverage

* :ghpull:`17269`: Fix ConciseDateFormatter when plotting a range included in a second

* :ghpull:`18063`: Remove un-used trivial setters and getters

* :ghpull:`18046`: Discourage references in section headings.

* :ghpull:`18042`: scatter: Raise if unexpected type of ``s`` argument.

* :ghpull:`18028`: Super-ify parts of the code base, part 1

* :ghpull:`17902`: Fix figure size in path effects guide

* :ghpull:`17899`: Add missing space in cairo error

* :ghpull:`17888`: Add _repr_png_ and _repr_html_ to Colormap objects.

* :ghpull:`17883`: Remove Python 3.6 compatibility shims

* :ghpull:`17889`: Minor doc fixes

* :ghpull:`17879`: Link to style-file example page in style tutorial

* :ghissue:`19275`: Double specifications of plot attributes

* :ghissue:`15066`: Feature request: stem3

* :ghissue:`19209`: Segfault when trying to create gigapixel image with agg backend

* :ghissue:`16376`: ``SymLogNorm`` and ``SymLogScale`` give inconsistent results....

* :ghissue:`19239`: _make_norm_from_scale needs to process values

* :ghissue:`16552`: Scatter autoscaling still has issues with log scaling and zero values

* :ghissue:`19206`: matplotlib.cbook.Grouper: Example raise exception:

* :ghissue:`19203`: Date Tick Labels example

* :ghissue:`18581`: Add a check in check_figures_equal that the test did not accidentally plot on non-fixture figures

* :ghissue:`18563`: Create a RangeSlider widget

* :ghissue:`19099`: axisartist axis_direction bug

* :ghissue:`19171`: 3D surface example bug for non-square grid

* :ghissue:`18112`: set_{x,y,z}bound 3d limits are not persistent upon interactive rotation

* :ghissue:`16123`: test_dpi_ratio_change fails on Windows/Qt5Agg

* :ghissue:`15796`: [DOC] PDF build of matplotlib own documentation crashes with LaTeX error "too deeply nested"

* :ghissue:`19091`: 3D Axes don't work in SubFigures

* :ghissue:`18386`: Path3DCollection.set_color(self, c) does not change the color of scatter points.

* :ghissue:`8946`: Axes with sharex can have divergent axes after setting tick markers

* :ghissue:`2294`: tex option not respected by date x-axis

* :ghissue:`18717`: Tick formatting issues on horizontal histogram with datetime on 3.3.2

* :ghissue:`12636`: Characters doesn't display correctly when figure saved as pdf with a custom font

* :ghissue:`18377`: Matplotlib picks a headless backend on Linux if Wayland is available but X11 isn't

* :ghissue:`5970`: pyplot.scatter raises obscure error when mistakenly passed a third string param

* :ghissue:`17936`: documenattion and behavior do not match for suppressing (PDF) metadata

* :ghissue:`17932`: latex textrm does not work in Cairo backend

* :ghissue:`17878`: flipping of imshow in specgram

* :ghissue:`6118`: consider using qtpy for qt abstraction layer

* :ghissue:`17908`: rcParams restrictions on frame_formats are out of sync with supported values (HTMLWriter)

* :ghissue:`17855`: Add Hatch Example to gallery

* :ghissue:`15821`: Should constrained_layout work as plt.figure() argument?

* :ghissue:`15616`: Colormaps should have a ``_repr_html_`` that is an image of the colormap

* :ghissue:`17652`: NEP 29 : Stop support fro Python 3.6 soon ?

* :ghissue:`11095`: Repeated plot calls with xunits=None throws exception

* :ghissue:`17733`: Rename "array" (and perhaps "fields") section of Axes API

As with text produced in the Agg backend (see :ref:`the previous what's new

entry <whats-new-3-2-0-kerning>` for examples), PDFs now include kerning in

Fully-fractional HiDPI in QtAgg