[Optimization] Switch from eval to create_function

[lisachenko]

Instead of building closure with eval at https://github.com/lisachenko/php-deal/blob/master/src/PhpDeal/Aspect/ContractCheckerAspect.php#L149:

if (!$invoker) {
    $invoker = function () {
        extract(func_get_arg(0));
        return eval('return ' . func_get_arg(1) . '; ?>');
    };
}

I can use a create_function or even additional cache file with definition of function body to optimize invocation of methods with contracts.

[lisachenko]

create_function is deprecated since 7.2.0, so this approach is no-go anymore.