Remove "action" from Actor functions that don't actually need it

- An actor function really only needs to be an action function if:
  1. It can be called with no parameters specified, either because it takes
     none or because all its parameters are optional. This lets SetState()
     call it directly without creating a wrapper function for it.
  2. It wants access to the callingstate or stateowner parameters. Most
     functions don't care about them, so passing them is superfluous.

src/thingdef/thingdef_exp.h

@@ -881,6 +881,7 @@ public:
 	ExpEmit Emit(VMFunctionBuilder *build, bool tailcall);
 	bool CheckEmitCast(VMFunctionBuilder *build, bool returnit, ExpEmit &reg);
 	unsigned GetArgCount() const { return ArgList == NULL ? 0 : ArgList->Size(); }
+	PFunction *GetFunction() const { return Function; }
 	VMFunction *GetVMFunction() const { return Function->Variants[0].Implementation; }
 	bool IsDirectFunction();
 };

src/thingdef/thingdef_expression.cpp

@@ -3844,7 +3844,7 @@ VMFunction *FxReturnStatement::GetDirectFunction()
 	// then it can be a "direct" function. That is, the DECORATE
 	// definition can call that function directly without wrapping
 	// it inside VM code.
-	if (Call != NULL && Call->GetArgCount() == 0)
+	if (Call != NULL && Call->GetArgCount() == 0 && (Call->GetFunction()->Flags & VARF_Action))
 	{
 		return Call->GetVMFunction();
 	}