[freeflow][upwindfluxvars] Use given velocity value at boundary

See merge request !1551

* Use boundary velocity v_j in term (v_i*v_j) both for upwinding and
  central average
* do not use upwinding for kovasznay test
* update reference solutions for kovasznay and angeli test

* Remove unused code and simplify

[test][geometry] Fix helper func specialization with dimworld

See merge request !1554

[timeloop] Remove additional scaling, epsilon is already relative

Closes #685

See merge request !1552

Feature/container variable precision

See merge request !1553

Remove superfluous entries in connectivity maps

Closes #537

See merge request !1524

The default 6 is the default of std::setprecision.
The io manipulators only affect floating point numbers.
If a number is exact only these digits will be printed (no zeros are
appended)

* delete wrong comments
* add better descriptions

Some fixes for coupling moving meshes.

See merge request !1545

[geometryisection] introduce policy classes for intersections

See merge request !1541

[facet][mpfa][fix] fix additional derivatives for numEq > 1

See merge request !1550

[staggered][geometry] Store two parallel distances per svcf lateral axis, not three

See merge request !1543

[test][staggered][discretization] make test 3d, write out all distance (cell centered and parallel widths)

Improve TimeloopBase

Closes #679

See merge request !1534