Unify leaf nodes with internal nodes and container nodes

Previously the leaf nodes were a separate type, and internal nodes and container
nodes were represented by the same type. This changes the representation such
that all nodes are represented by sharing_nodet. This will allow an internal
node to directly point to a leaf node (instead of having to point to a container
node which in turn points to a leaf node).

Author: danpoe

src/util/sharing_map.h

@@ -193,10 +193,8 @@ class sharing_mapt
   typedef std::vector<key_type> keyst;
 
 protected:
-  typedef sharing_node_innert<key_type, mapped_type> innert;
-  typedef sharing_node_leaft<key_type, mapped_type> leaft;
-
-  typedef sharing_node_baset baset;
+  typedef sharing_nodet<key_type, mapped_type> innert;
+  typedef sharing_nodet<key_type, mapped_type> leaft;
 
   typedef typename innert::to_mapt to_mapt;
   typedef typename innert::leaf_listt leaf_listt;
@@ -721,7 +719,7 @@ ::count_unmarked_nodes(
       for(const auto &l : ll)
       {
         const unsigned leaf_use_count = l.use_count();
-        const void *leaf_raw_ptr = &l.read();
+        const void *leaf_raw_ptr = &l.read_leaf();
 
         if(leaf_use_count >= 2)
         {