Added const basis functions and implemented new interface methods.

[[Imported from SVN: r185]]

fem/lagrangebase.hh

@@ -642,7 +642,6 @@ namespace Dune {
           FastBaseFunctionSet < LagrangeDiscreteFunctionSpace
               < FunctionSpaceType , GridType, polOrd   > > >
   {
-
     typedef DiscreteFunctionSpaceInterface <
         FunctionSpaceType , GridType,
         LagrangeDiscreteFunctionSpace < FunctionSpaceType , GridType, polOrd >,
@@ -697,6 +696,13 @@ namespace Dune {
       return (*baseFuncSet_.get( type ));
     };
 
+    //! return true if we have continuous discrete functions
+    bool continuous ( ) const
+    {
+      bool ret = (polOrd == 0) ? false : true;
+      return ret;
+    }
+
     //! get maximal global polynom order
     int polynomOrder ( ) const
     {