make fvector test compile again (this should be revised).

[[Imported from SVN: r6375]]

dune/common/fvector.hh

@@ -81,7 +81,7 @@ namespace Dune {
 
     //! Constructor making vector with identical coordinates
     template<class C>
-    explicit FieldVector (const DenseVector<C> & x)
+    FieldVector (const DenseVector<C> & x)
     {
       assert(x.size() == SIZE);
       for (size_type i = 0; i<SIZE; i++)