[!715] [bugfix] correct bug in division of FieldVector by scalar

Merge branch 'issue/fvector_divide_scalar' into 'master'

ref:core/dune-common

### Summary

Replaced * by / in vector-space division of FieldVector by scalar

See merge request [core/dune-common!715]

  [core/dune-common!715]: gitlab.dune-project.org/core/dune-common/merge_requests/715

dune/common/fvector.hh

@@ -244,7 +244,7 @@ namespace Dune {
       FieldVector<typename PromotionTraits<value_type,Scalar>::PromotedType,SIZE> result;
 
       for (size_type i = 0; i < vector.size(); ++i)
-        result[i] = vector[i] * scalar;
+        result[i] = vector[i] / scalar;
 
       return result;
     }