Merged requested to merge feature/facetcoupling-with-domainmarkers into master
The coupling manager can now return the element a bulk scvf is coinciding with. This element can be used to obtain the domain marker of the lowdim element by accessing the lowdim problem via the coupling manager and obtaining the marker from the spatial params. This can be used to set different coupling conditions (Dirichlet/Neumann) depending on the marker. Additionally, we allow extraction of a sub-domain specific grid data object from the wrapper. This object can then be passed directly to the sub-domain's spatial parameters.