This is a bugfix release to resolve xr.corr & xr.map_blocks when dask is not installed.
It also includes performance improvements in unstacking to a sparse array and a
number of documentation improvements.
Many thanks to the 20 contributors:
Aaron Spring, Alexandre Poux, Deepak Cherian, Enrico Minack, Fabien Maussion,
Giacomo Caria, Gijom, Guillaume Maze, Illviljan, Joe Hamman, Joseph Hardin, Kai
Mühlbauer, Matt Henderson, Maximilian Roos, Michael Delgado, Robert Gieseke,
Sebastian Weigand and Stephan Hoyer.