Add invocation queue to DrivenEngine, use it for lua source

luprex/cpp/core/lpxserver.cpp

@@ -31,7 +31,7 @@ public:
     Gui gui_;
 
 public:
-    virtual void event_init(std::string_view srcpk, int argc, char *argv[]) {
+    virtual void event_init(std::string_view srcpk, int argc, char *argv[]) override {
         // Create the master world model.
         master_.reset(new World(WORLD_TYPE_MASTER));
 
@@ -166,9 +166,13 @@ public:
         return true;
     }
     
-    virtual void event_update() {
-        // If the driver has reloaded the source, put it into master model.
-        master_->update_source(get_lua_source_pack());
+    virtual void event_update() override {
+        // Execute any queued invocations.
+        // We just feed these directly into the master model.
+        eng::vector<UniqueInvocation> invocations = get_queued_invocations();
+        for (const UniqueInvocation &inv : invocations) {
+            master_->invoke(*inv);
+        }
 
         // Check for keyboard input on stdin.
         while (true) {