Merge branch 'mpistubs' into 'master'

move mpi stubs into walberla::mpistubs namespace

Closes #18

See merge request !17

src/core/mpi/MPIWrapper.h

@@ -45,7 +45,11 @@
 
 #endif
 
-
+namespace walberla {
+namespace mpistubs {
+    //empty namespace which can be used
+} // namespace mpistubs
+} // namespace walberla
 
 #ifdef WALBERLA_BUILD_WITH_MPI
 
@@ -73,6 +77,7 @@
 
 namespace walberla {
 
+namespace mpistubs {
 
 
 typedef int MPI_Comm;
@@ -258,6 +263,9 @@ inline double MPI_Wtime() { WALBERLA_MPI_FUNCTION_ERROR }
 
 #undef WALBERLA_MPI_FUNCTION_ERROR
 
+} // namespace mpistubs
+using namespace mpistubs;
+
 } // namespace walberla
 
 #endif // WALBERLA_BUILD_WITH_MPI