version 1.3.1 (tag v1.3.1rel)
=============================
* add parallel IO capabilities. netcdf-c and hdf5 must be compiled with MPI
support, and mpi4py must be installed. To open a file for parallel access,
use `parallel=True` in `Dataset.__init__` and optionally pass the mpi4py Comm instance
using the `comm` kwarg and the mpi4py Info instance using the `info` kwarg.
IO can be toggled between collective and independent using `Variable.set_collective`.
See `examples/mpi_example.py`. Issue #717, pull request #716.
Minimum cython dependency bumped from 0.19 to 0.21.
* Add optional `MFTime` calendar overload to use across all files, for example,
`'standard'` or `'gregorian'`. If `None` (the default), check that the calendar
attribute is present on each variable and values are unique across files raising
a `ValueError` otherwise.
* Allow _FillValue to be set for vlen string variables (issue #730).