Add support for saving/restoring of chaiscript engine state.

include/chaiscript/language/chaiscript_engine.hpp

@@ -339,6 +339,32 @@ namespace chaiscript
             return *this;
         }
 
+        struct State
+        {
+            std::set<std::string> loaded_files;
+            typename Eval_Engine::State engine_state;
+        };
+
+        State get_state()
+        {
+          boost::lock_guard<boost::recursive_mutex> l(use_mutex);
+          boost::shared_lock<boost::shared_mutex> l2(mutex);
+
+          State s;
+          s.loaded_files = loaded_files;
+          s.engine_state = engine.get_state();
+          return s;
+        }
+
+        void set_state(const State &t_state)
+        {
+          boost::lock_guard<boost::recursive_mutex> l(use_mutex);
+          boost::shared_lock<boost::shared_mutex> l2(mutex);
+
+          loaded_files = t_state.loaded_files;
+          engine.set_state(t_state.engine_state);
+        }
+
         /**
          * Adds an object to the system: type, function, object
          */