remove references to cyordereddict (#2750)

Author: Joe Hamman

doc/installing.rst

@@ -45,8 +45,6 @@ For accelerating xarray
 - `bottleneck <https://github.com/kwgoodman/bottleneck>`__: speeds up
   NaN-skipping and rolling window aggregations by a large factor
   (1.1 or later)
-- `cyordereddict <https://github.com/shoyer/cyordereddict>`__: speeds up most
-  internal operations with xarray data structures (for python versions < 3.5)
 
 For parallel computing
 ~~~~~~~~~~~~~~~~~~~~~~

doc/whats-new.rst

@@ -28,6 +28,8 @@ Breaking changes
   `DataArray` are deprecated and will be removed in a future release.
   (:issue:`1188`)
   By `Maximilian Roos <https://github.com/max-sixty>`_.
+- `cyordereddict` is no longer used as an optional dependency (:issue:`2744`).
+  By `Joe Hamman <https://github.com/jhamman>`_.
 
 Enhancements
 ~~~~~~~~~~~~

xarray/util/print_versions.py

@@ -102,7 +102,6 @@ def show_versions(as_json=False):
         ("cfgrib", lambda mod: mod.__version__),
         ("iris", lambda mod: mod.__version__),
         ("bottleneck", lambda mod: mod.__version__),
-        ("cyordereddict", lambda mod: mod.__version__),
         ("dask", lambda mod: mod.__version__),
         ("distributed", lambda mod: mod.__version__),
         ("matplotlib", lambda mod: mod.__version__),