MPI support #284

Job	Run time
static builds (ubuntu-latest, stable)	1m 23s
static builds (windows-latest, stable-msvc)	5m 52s
mpi-runner	1m 46s
Address sanitizer	1m 26s
static builds (windows-latest, stable-gnu)	5m 31s
conda (ubuntu, conda-forge, stable)	46s
static builds (macos-11, stable)	4m 28s
conda (windows, conda-forge, stable)	2m 52s
rustfmt	1m 31s
static builds (macos-latest, stable)	1m 38s
conda (macos, conda-forge, stable)	57s
test apt (stable)	40s
test apt (beta)	43s
test apt (nightly)	43s
	30m 16s

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