add support for vectorization library VC

This branch adds support for the Vc library, which add support for vectorization, including an abstraction for intrisics.

We have been using in EXA-Dune and I belive that the integration of vectorization support into the core-Dune is something Dune in general can benefit from. A separate branch I'm preparing for ISTL will add support for multiple RHS vectors using vectorization.

The branch collects a set of helper classes which allow to add vectorization support to your code with moderate effort. Mainly this means that we have a couple of utility functions, which work for scalar data types, ranges and SIMD data types alike.

dune/common/rangeutilities.hh

+#ifndef DUNE_COMMON_RANGE_UTILITIES_HH
+#define DUNE_COMMON_RANGE_UTILITIES_HH
+
+#include <dune/common/typetraits.hh>
+#include <utility>
+#include <type_traits>
+#include <bitset>
+
+namespace Dune
+{
+  template <typename T,
+            typename std::enable_if<!is_range<T>::value, int>::type = 0>
+  const T & max_value(const T & v) { return v; };
+
+  template <typename T,
+            typename std::enable_if<is_range<T>::value, int>::type = 0>
+  typename T::value_type
+  max_value(const T & v) {
+    using std::max;
+    typename T::value_type m;
+    for (const auto & e : v)
+      m = max(e,m);
+    return m;
+  };
+
+  template <typename T,
+            typename std::enable_if<!is_range<T>::value, int>::type = 0>
+  T & min_value(const T & v) { return v; };
+
+  template <typename T,
+            typename std::enable_if<is_range<T>::value, int>::type = 0>
+  typename T::value_type
+  min_value(const T & v) {
+    using std::min;
+    typename T::value_type m;
+    for (const auto & e : v)
+      m = min(e,m);
+    return m;
+  };
+
+  template <typename T,
+            typename std::enable_if<!is_range<T>::value, int>::type = 0>
+  bool any_true(const T & v) { return v; };
+
+  template <typename T,
+            typename std::enable_if<is_range<T>::value, int>::type = 0>
+  bool any_true(const T & v) {
+    bool b = false;
+    for (const auto & e : v)
+      b = b or bool(e);
+    return b;
+  };
+
+  template<std::size_t N>
+  bool any_true(const std::bitset<N> & b)
+  {
+    return b.any();
+  }
+
+  template <typename T,
+            typename std::enable_if<!is_range<T>::value, int>::type = 0>
+  bool all_true(const T & v) { return v; };
+
+  template <typename T,
+            typename std::enable_if<is_range<T>::value, int>::type = 0>
+  bool all_true(const T & v) {
+    bool b = true;
+    for (const auto & e : v)
+      b = b and bool(e);
+    return b;
+  };
+
+  template<std::size_t N>
+  bool all_true(const std::bitset<N> & b)
+  {
+    return b.all();
+  }
+
+}
+
+#endif // DUNE_COMMON_RANGE_UTILITIES_HH