src: Updating code style to conform (more or less) to ndn-cxx style

Also, adding .clang-format that describes the applied style. Note that
this style requires a slightly customized version of clang-format.
diff --git a/utils/trie/empty-policy.hpp b/utils/trie/empty-policy.hpp
index c610717..7d077b6 100644
--- a/utils/trie/empty-policy.hpp
+++ b/utils/trie/empty-policy.hpp
@@ -28,29 +28,47 @@
 /**
  * @brief Traits for empty (bogus) replacement policy
  */
-struct empty_policy_traits
-{
+struct empty_policy_traits {
   /// @brief Name that can be used to identify the policy (for NS-3 object model and logging)
-  static std::string GetName () { return ""; }
+  static std::string
+  GetName()
+  {
+    return "";
+  }
 
   typedef void* policy_hook_type;
 
-  template<class Container> struct container_hook { typedef void* type; };
+  template<class Container>
+  struct container_hook {
+    typedef void* type;
+  };
 
-  template<class Base,
-           class Container,
-           class Hook>
-  struct policy 
-  {
-    struct type
-    {
-      inline type (Base &base) {}
-      
-      inline void update (typename Container::iterator) { }
-      inline bool insert (typename Container::iterator) { return true; }
-      inline void lookup (typename Container::iterator item) { }
-      inline void erase (typename Container::iterator item) { }
-      inline void clear () { }
+  template<class Base, class Container, class Hook>
+  struct policy {
+    struct type {
+      inline type(Base& base)
+      {
+      }
+
+      inline void update(typename Container::iterator)
+      {
+      }
+      inline bool insert(typename Container::iterator)
+      {
+        return true;
+      }
+      inline void
+      lookup(typename Container::iterator item)
+      {
+      }
+      inline void
+      erase(typename Container::iterator item)
+      {
+      }
+      inline void
+      clear()
+      {
+      }
     };
   };
 };