Merge branch 'feature/example-tracer-cleanup' into 'master'
Feature/example tracer cleanup
See merge request !2513 (merged)
(cherry picked from commit e9f526d4)
82386d67 [example][1ptracer] Remove some unncessary includes a3b08f9a [example][1ptracer] Update doc after changing the random distribution 884677ab [example][1ptracer] Lower solver requirements (only use dune-istl)