norm2 -> two_norm

first version of grid-test (to be committed tomorrow) already catched
a bug :)

[[Imported from SVN: r1004]]

grid/uggrid/ugintersectionit.cc

@@ -150,7 +150,7 @@ namespace Dune {
 #undef V3_VECTOR_PRODUCT
 
     // normalize
-    outerNormal_ *= (1/outerNormal_.norm2());
+    outerNormal_ *= (1/outerNormal_.two_norm());
 #endif
     return outerNormal_;