Refactor to remove dependency of DrivenEngine on World

luprex/cpp/core/lpxserver.cpp

@@ -23,6 +23,8 @@ using ClientVector = eng::vector<UniqueClient>;
 
 class LpxServer : public DrivenEngine {
 public:
+    EngineWrapper *wrapper_;
+    std::unique_ptr<World> world_;
     ClientVector clients_;
     PrintChanneler print_channeler_;
     HttpChannelMap http_client_channels_;
@@ -32,13 +34,14 @@ public:
     lua_State *lua_syntax_checker_;
 
 public:
-    LpxServer()
+    LpxServer(EngineWrapper *w) : wrapper_(w)
     {
         // Create a little lua interpreter for syntax checking only.
         lua_syntax_checker_ = LuaCoreStack::newstate(eng::l_alloc);
 
         // Create the master world model.
         world_.reset(new World(WORLD_TYPE_MASTER));
+        world_->expose_world_to_driver(wrapper_);
 
         // Create the admin actor.  Note: there isn't any 'init' function yet.
         actor_id_ = world_->create_login_actor();
@@ -60,6 +63,7 @@ public:
     }
 
     ~LpxServer() {
+        unexpose_world_to_driver(wrapper_);
         lua_close(lua_syntax_checker_);
     }