Use elementwise size in node vertex consistency check (#316)
* use elementwise size in node vertex consistency check
* add comment explaining maximum(..., 1)
* use test based on maximum absolute vertex coordinate instead of element size, and add tests
* assume absolute and relative tolerances are the same for now
* add test for false negatives
* zero-size -> zero-D
* improve vertex consistency check error message
* use a specific exception type for consistency check
* improve tests
* just use relative tolerance and skip dim==0 case
* only do consistency check in debug run
* Reenable 0D tests, remove 1e-5 crit tol scaling, take into account abs tol in node-vert-consistency test tests
Co-authored-by: Andreas Kloeckner <inform@tiker.net>