[IDE Classes] Add return types for entity repositories (#7251)
[IDE Classes] Add return types for entity repositories (#7251)

What about telling the IDE the return types of the `find()`/`findOneBy()`/`findAll()`/`findBy()`/`matching()` of custom entity repositories?

I don't know if phpstorms support a syntax like the one provided by the following code- if not, phpstorm users should give a thumb up at https://youtrack.jetbrains.com/issue/WI-27832.

```php
override(\Concrete\Core\Entity\Express\EntityRepository::find(0), map([
  '' => 'Concrete\Core\Entity\Express\Entity|null',
]));
```

BTW I just updated my Eclipse+PDT plugin to support it.

Sample application:

![immagine](https://user-images.githubusercontent.com/928116/47566542-615be180-d92c-11e8-988f-0cad4125ea6e.png)

concrete5/concrete5,mlocati/concrete5,olsgreen/concrete5,deek87/concrete5,haeflimi/concrete5,mlocati/concrete5,hissy/concrete5,hissy/concrete5,concrete5/concrete5,MrKarlDilkington/concrete5,MrKarlDilkington/concrete5,deek87/concrete5,deek87/concrete5,rikzuiderlicht/concrete5,mlocati/concrete5,hissy/concrete5,concrete5/concrete5,biplobice/concrete5,jaromirdalecky/concrete5,biplobice/concrete5,mainio/concrete5,mainio/concrete5,deek87/concrete5,biplobice/concrete5,jaromirdalecky/concrete5,haeflimi/concrete5,biplobice/concrete5,mainio/concrete5,concrete5/concrete5,haeflimi/concrete5,jaromirdalecky/concrete5,mlocati/concrete5,haeflimi/concrete5,jaromirdalecky/concrete5,MrKarlDilkington/concrete5,rikzuiderlicht/concrete5,olsgreen/concrete5,rikzuiderlicht/concrete5,olsgreen/concrete5,hissy/concrete5