Make pre-defined property page non-movable

Fixed properties are fixed for a reason therefore prevent a property page that represents pre-defined property to be non-movable.

Relates to #600.
I was about to complain about the name here, though then figured that is not the main issue. Why not have a service, say `MovabilityDetector` (funky name, maybe you find a better one), which has an `isMovable( Title $title )` method? This method would return a boolean indicating movability as far as SMW is concerned (naming needs to be changed in such a way this limited context is clear). Then in your hook you can do

```php
$functionHookDefinition['TitleIsMovable'] = function ( $title, &$isMovable ) {
    $isMovable = $isMovable && getMyGlobalFactoryThing()->newMovabilityDetector()->isMovable( $title );
}
```

This also moves into the direction of avoiding global state usage beyond the entry point. By talking to `DIProperty::newFromUserLabel`, you are using this array with the predefined things as global state. That could be injected (perhaps in encapsulated form) by the factory into the service.