Managers can now be directly declared in a Document eg::
```python
class CustomQuerySetManager(QuerySetManager):
@staticmethod
def get_queryset(doc_cls, queryset):
return queryset(is_published=True)
class Post(Document):
is_published = BooleanField(default=False)
published = CustomQuerySetManager()
```
Refactored the name of the `_manager_func` to `get_queryset` to mark it as
part the public API. If declaring a Manager with a get_queryset method, it
should be a staticmethod, that accepts the document_class and the queryset.
Note - you can still use decorators in fact in the example below,
we effectively do the same thing as the first example and is much less verbose.
```python
class Post(Document):
is_published = BooleanField(default=False)
@queryset_manager
def published(doc_cls, queryset):
return queryset(is_published=True)
```
Thanks to @theojulienne for the initial impetus and code sample #108
1126c85903