2.4 with deprecated alugrid removed

This pr drops the old alugrid names, which were removed from dune-grid in the 2.4 release. One can now use dune-fem 2.4 with the core modules 2.4 and with alugrid as well as dune-alugrid.

This pr also includes a dubious commit 1bb397ab, where I had no idea how to fix the compile error and just followed the compilers suggesttion; you might want to take a look at this.