Bugfix/geometrygrid various

I looked at the patch, but I wouldn't know how to test it. Can you please extend the grid tests in such a way that the bugs you claim to fix are tested there? Thanks.

There is no need for an extra test; the bug in the computation of the integrationOuterNormal() is already triggered by the grid test in case of a non-conforming GeometryGrid instance. Unfortunately, we can't create a non-conforming grid for testing purposes right now, unless we assume users have UG installed. For your convenience I'll attach a minimal example creating a non-conforming host grid and showing the bug (make sure you run it with debugging flags!).

test_geometrygrid.cc cube2d.dgf

@oliver.sander : Actually, the bug is quite obvious (at least to me). Unless you object, I will merge this one without further discussion.

I do not doubt that the code is buggy. But I would have liked to use the occasion to get our test improved. A separate test like the one Christoph sent is of no use for that, unfortunately. I do not object to merging.

Added 17 commits:

• 3451fec7...92d3fbc4 - 15 commits from branch master
• 190e9c63 - [bugfix] Fix integrationOuterNormal for non-conforming intersections in GeometryGrid
• 8b22b8c7 - [bugfix] Fix swap on PersistentContainerWrapper

I rebased to master and renamed the offending variables.

Any objections to merging? Otherwise I'll to so this afternoon.

mentioned in commit 5aa798c7

Status changed to merged

Mentioned in commit 5aa798c7