[!276] Feature/use custom geometry transformation for blockstructured

Merge branch 'feature/use-custom-geometry-transformation' into 'master'

ref:dominic/dune-perftool This computes the determinant and jacobian inverse
transposed directly within loopy and does not call the corresponding grid
functions. Using some simple precomputations this is faster if
number_of_blocks>=2.

This also allows straight forward vectorization for unstructured grids.

I don't know how the computation of the geometry transformation is done in the
sumfactored case, but maybe there is some overlap, which could be reduced.

See merge request [dominic/dune-perftool!276]

  [dominic/dune-perftool!276]: gitlab.dune-project.org/dominic/dune-perftool/merge_requests/276