Merge branch 'feature/generalize-re-size' into 'master'

Allow `ReferenceElement::size(i,c,cc)` for `cc<c`

See merge request !93
6 jobs for master in 2 minutes and 52 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #43644
duneci
debian:10 clang-6-libcpp-17

00:02:29

passed #43643
duneci
debian:10 gcc-8-noassert-17

00:02:52

passed #43646
duneci
debian:9 clang-3.8-14

00:02:13

passed #43645
duneci
debian:9 gcc-6-14

00:02:11

passed #43647
duneci
ubuntu:16.04 gcc-5-14

00:02:09

passed #43648
duneci
ubuntu:18.04 clang-6-17

00:02:20