rework syntax checks, rework priority correction algorithm

src/test-cases.cpp

@@ -99,7 +99,10 @@ TEST(tree_proper_test_1)
 TEST(tree_proper_test_2)
 {
 	std::vector<Expression::Token> o = Parser::tokenize_input("(1**5 * (1-2-3-4-5-6-7-8))");
-	Syntax::post_process(o);
+	if (Syntax::prepare_token_vector(o))
+	{
+		return 1;
+	}
 	std::vector<Expression::Operation> ov = Syntax::build_op_vector(o);
 
 	return 0;