[!385] [bugfix][fastdg] Fix pattern assembly in FastDG
Merge branch 'bugfix/fastdg-pattern-assembly' into 'master'
ref:pdelab/dune-pdelab This fixes a bug that originate from a partial exadune port. In Exadune, the pattern base classes have a fast version, which was not ported to PDELab. However, in the absence of these, the PatternEngine of the FastDGGridOperator needs to be more clever and only operate on one entry of each block.
See merge request pdelab/dune-pdelab!385
(cherry picked from commit 23823f6e)
1db0866a [bugfix][fastdg] Fix pattern assembly in FastDG