Get libc++ on ubuntu 14.04 working

The std::is_member_function_pointer<> template is broken on this version
of the libc++ standard library for const member functions.

To get ChaiScript to work with this, we had to work around the use of
automatically generated std::function wrappers in many cases. This
actually cleaned up the code in a few places and muddied it up in one.

include/chaiscript/dispatchkit/bootstrap.hpp

@@ -357,7 +357,9 @@ namespace chaiscript
       template<typename Function>
       static std::function<std::vector<Boxed_Value> (const dispatch::Proxy_Function_Base*)> return_boxed_value_vector(const Function &f)
       {
-        return std::bind(&do_return_boxed_value_vector<Function>, f, std::placeholders::_1);
+        return [f](const dispatch::Proxy_Function_Base *b) {
+          return do_return_boxed_value_vector(f, b);
+        };
       }