Implemented World::probe_lua_call and tested

luprex/cpp/core/world.hpp

@@ -242,7 +242,14 @@ public:
     // from the stringstream.  If the lua expression returns a
     // value, that is also printed to the stringstream.
     //
-    eng::string probe_lua(int64_t actor_id, std::string_view lua);
+    eng::string probe_lua_expr(int64_t actor_id, std::string_view lua);
+
+    // Probe that calls lua function, passing arguments.
+    //
+    // Print statements are discarded.  The lua function may return a vector
+    // of values.  If so, the values are packed into a StreamBuffer.
+    //
+    void probe_lua_call(int64_t place_id, int64_t actor_id, std::string_view datapack, StreamBuffer *retvals);
 
     // Invoke an Invocation object.
     //