Merge branch 'feature/cleanup-poisson-mfem' into 'master'

Cleanup poisson-mfem

See merge request !341
8 jobs for master in 34 minutes and 8 seconds (queued for 8 seconds)
Status Name Job ID Coverage
  Test
passed debian:10 clang-7-libcpp-17 #297526
duneci

00:14:52

passed debian:10 gcc-7-17 #297524
duneci

00:18:19

passed debian:10 gcc-8-noassert-17 #297525
duneci

00:26:33

passed debian:11 gcc-10-20 #297528
duneci

00:33:12

passed debian:11 gcc-9-20 #297527
duneci

00:34:07

passed ubuntu:18.04 clang-5-17 #297529
duneci

00:06:14

passed ubuntu:18.04 clang-6-17 #297530
duneci

00:06:09

passed ubuntu:20.04 clang-10-20 #297531
duneci

00:16:41