[bugfix] Fix jacobian part of Piola transformations

Since jacobian(Inverse)Transposed may be a sparse matrix (e.g. DiagonalMatrix for YaspGrid) we must not use jacobian(Inverse)Transposed[i][j]. Instead iterate over the sparse row entries using sparseRange.

This is now covered by extending the test of GlobalValuedFiniteElement to YaspGrid and higher order RT elements.

added bugfix label

mentioned in issue #68

enabled an automatic merge when the pipeline for 96858a98 succeeds

mentioned in commit 7bfbdd0c

merged

Thanks, what a blatant bug!

This needs to go into 2.8 as well.

picked the changes into the branch cherry-pick-7bfbdd0c with commit f1f963f6

mentioned in commit f1f963f6

mentioned in merge request !339 (merged)