Function chained call

This will allow such syntax:
```php
(function(){})(); // call an closure
```

```php
(func())(); // function chained calls
```

this patch is based on the @nikic 's instance call one.  maybe we can merge them together..

btw: there are some invalid reads report while run with valgrind,, but it seems introduces by nikic's patch,

I will keep looking them.