Generic cleanup and dead code removal in deferred model field loading
and model.__reduce__().
Also fixed an issue where if an inherited model with a parent field
chain parent_ptr_id -> id would be deferred loaded, then accessing
the id field caused caused a database query, even if the id field's
value is already loaded in the parent_ptr_id field.
* Removed `Manipulator`, `AutomaticManipulator`, and related classes.
* Removed oldforms specific bits from model fields:
* Removed `validator_list` and `core` arguments from constructors.
* Removed the methods:
* `get_manipulator_field_names`
* `get_manipulator_field_objs`
* `get_manipulator_fields`
* `get_manipulator_new_data`
* `prepare_field_objs_and_params`
* `get_follow`
* Renamed `flatten_data` method to `value_to_string` for better alignment with its use by the serialization framework, which was the only remaining code using `flatten_data`.
* Removed oldforms methods from `django.db.models.Options` class: `get_followed_related_objects`, `get_data_holders`, `get_follow`, and `has_field_type`.
* Removed oldforms-admin specific options from `django.db.models.fields.related` classes: `num_in_admin`, `min_num_in_admin`, `max_num_in_admin`, `num_extra_on_change`, and `edit_inline`.
* Serialization framework
* `Serializer.get_string_value` now calls the model fields' renamed `value_to_string` methods.
* Removed a special-casing of `models.DateTimeField` in `core.serializers.base.Serializer.get_string_value` that's handled by `django.db.models.fields.DateTimeField.value_to_string`.
* Removed `django.core.validators`:
* Moved `ValidationError` exception to `django.core.exceptions`.
* For the couple places that were using validators, brought over the necessary code to maintain the same functionality.
* Introduced a SlugField form field for validation and to compliment the SlugField model field (refs #8040).
* Removed an oldforms-style model creation hack (refs #2160).
git-svn-id: http://code.djangoproject.com/svn/django/trunk@8616 bcc190cf-cafb-0310-a4f2-bffc1f526a37
