make progress on #885 (closed) (@martins)
#1047 (closed) (@DennisGlaeser)
!2792 (merged),!2793 (merged) (@melaniel)
!2708 (merged) (@timok)
!2734 (closed) (@nedc) (moved to next dumux day)
see #1062 (closed): @heck, @yue, @IvBu
all: test !2769 (closed) and report if test fails