DOC: final merge up of API changes

Author: tacaswell

doc/api/api_changes.rst

@@ -14,14 +14,22 @@ API Changes in 2.2.0
 ====================
 
 ..
-
   .. toctree::
      :glob:
      :maxdepth: 1
 
      next_api_changes/*
 
 
+New dependency
+--------------
+
+`kiwisolver <https://github.com/nucleic/kiwi>`__ is now a required
+dependency to support the new constrained_layout,  see
+:ref:`sphx_glr_tutorials_intermediate_constrainedlayout_guide.py` for
+more details.
+
+
 Deprecations
 ------------
 
@@ -80,6 +88,10 @@ transparency of figure patches in the nbagg (or any other) backend,
 directly set ``figure.patch.facecolor``, or the ``figure.facecolor``
 rcParam.
 
+Deprecated `Axis.unit_data`
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Use `Axis.units` (which has long existed) instead.
 
 
 Removals
@@ -136,6 +148,12 @@ The following deprecated rcParams have been removed:
 
 
 
+Only accept string-like for Categorical input
+---------------------------------------------
+
+Do not accept mixed string / float / int input, only
+strings are valid categoricals.
+
 Removal of unused imports
 -------------------------
 Many unused imports were removed from the codebase.  As a result,
@@ -144,6 +162,13 @@ trying to import certain classes or functions from the "wrong" module
 :mod:`matplotlib.figure`) will now raise an `ImportError`.
 
 
+``Axes3D.get_xlim``, ``get_ylim`` and ``get_zlim`` now return a tuple
+---------------------------------------------------------------------
+
+They previously returned an array.  Returning a tuple is consistent with the
+behavior for 2D axes.
+
+
 Exception type changes
 ----------------------
 
@@ -261,14 +286,6 @@ and ::
 
 
 
-New dependency
---------------
-
-`kiwisolver <https://github.com/nucleic/kiwi>`__ is now a required
-dependency to support the new constrained_layout,  see
-:ref:`sphx_glr_tutorials_intermediate_constrainedlayout_guide.py` for
-more details.
-
 
 `Axes.imshow` clips RGB values to the valid range
 -------------------------------------------------