some minor fixes

i.e., removing redundant namespace open- and closings due to the fact
that the property system now resides in the 'Ewoms' namspace instead
of in 'Opm', and making the headercheck work for all headers.

examples/problems/fractureproblem.hh

@@ -25,6 +25,7 @@
 #define EWOMS_FRACTURE_PROBLEM_HH
 
 #include <ewoms/parallel/mpihelper.hh>
+#include <ewoms/models/discretefracture/discretefracturemodel.hh>
 
 #if HAVE_DUNE_ALUGRID
 #include <dune/alugrid/grid.hh>
@@ -46,8 +47,6 @@
 #include <opm/material/components/Dnapl.hpp>
 #include <ewoms/io/artgridmanager.hh>
 
-#include <ewoms/models/discretefracture/discretefracturemodel.hh>
-
 #include <dune/common/version.hh>
 #include <dune/common/fmatrix.hh>
 #include <dune/common/fvector.hh>