Merge branch 'use-range-based-for' into 'master'

GridGlueVtkWriter: use range-based for to interate over intersections

See merge request !47
4 jobs for master in 8 minutes and 28 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Test
passed #186168
duneci
dune:2.7 gcc-8 C++17

00:03:40

passed #186167
duneci
dune:git clang C++17

00:02:03

passed #186165
duneci
dune:git gcc-8 C++17

00:04:27

failed #186166
duneci
dune:git gcc-9 C++20

00:08:28

 
Name Stage Failure
failed
dune:git gcc-9 C++20 Test
--- Failed to build dune-grid-glue ---
Terminating dunecontrol due to previous errors!
+ exit 1
Uploading artifacts for failed job
Uploading artifacts...
junit/*.xml: found 1 matching files and directories

Uploading artifacts as "junit" to coordinator... ok
id=186166 responseStatus=201 Created token=h9csC3Rq
Cleaning up file based variables
ERROR: Job failed: exit code 1