Tests should be ported one by one in separate merge requests. In principle, the new implementations are available in !2201. Move changes from `problem_new.hh` and `main_new.hh` to `problem.hh`, `main.hh`and `properties.hh`. Be careful as !2201 is already partly outdated. !2830 is a port based on the current master. - [x] `navierstokes/angeli`: @heck - [x] `navierstokes/channel/1d`: @RoWin - [x] `navierstokes/channel/pipe`: @hanchuan - [x] `examples/liddrivencavity`: @nedc