fixed bug where elliptic_msfem did not work in parallel

Problem was that local grids got load-balanced, too
in constructor of SPGrid as StructuredGridFactory
always called the constructor using the MPI_Comm
and doing loadBalancing.
Conflicts:
	dune/multiscale/common/dirichletconstraints.cc
	dune/multiscale/common/dirichletconstraints.hh
	dune/multiscale/msfem/msfem_traits.hh
Hardcoded fine mesh corners to coarse mesh corners

Dunno why coarse mesh corners are hardcoded but
the current code made the fine mesh not cover
the whole domain as on each process, a fine mesh
was created that used the corners of the load-
balanced coarse mesh which are not the same as
those of the non-load-balanced.