Simplify mutex code by providing stubs that are do nothing during

CHAISCRIPT_NO_THREADS builds.

include/chaiscript/chaiscript_threading.hpp

@@ -13,6 +13,14 @@
 #pragma message ("ChaiScript is compiling without thread safety.")
 #endif
 
+/// \file
+///
+/// This file contains code necessary for thread support in ChaiScript.
+/// If the compiler definition CHAISCRIPT_NO_THREADS is defined then thread safety
+/// is disabled in ChaiScript. This has the result that some code is faster, because mutex locks are not required.
+/// It also has the side effect that the chaiscript::ChaiScript object may not be accessed from more than
+/// one thread simultaneously.
+
 namespace chaiscript
 {
   namespace detail
@@ -21,6 +29,12 @@ namespace chaiscript
     {
 
 #ifndef CHAISCRIPT_NO_THREADS
+      using boost::unique_lock;
+      using boost::shared_lock;
+      using boost::lock_guard;
+      using boost::shared_mutex;
+      using boost::recursive_mutex;
+
 
       template<typename T>
         class Thread_Storage
@@ -51,6 +65,32 @@ namespace chaiscript
         };
 
 #else
+      template<typename T>
+      class unique_lock 
+      {
+        public:
+          unique_lock(T &) {}
+      };
+
+      template<typename T>
+      class shared_lock 
+      {
+        public:
+          shared_lock(T &) {}
+          void unlock() {}
+      };
+
+      template<typename T>
+      class lock_guard 
+      {
+        public:
+          lock_guard(T &) {}
+      };
+
+      class shared_mutex { };
+
+      class recursive_mutex {};
+
 
       template<typename T>
         class Thread_Storage