* Fix problem where Model instancess are not considered subtypes of each other due to fallback_to_any = True. Fixes#52.
- Added a stub for __getstate__ to Model.
- Added a stub for clean() to Model.
- Correct arg type for sort_dependencies so they are covariant (Iterable rather than List).
Test ignores:
- Added some test ignores in cases where a model inherits from 2 different base models.
- Added some test ignores for cases that MyPy flags as errors due to variable redefinitions or imports that are incompatible types.
* Address review comment.
* Instead of using Literal types, overload QuerySet.values_list in the plugin. Fixes#43.
- Add a couple of extra type checks that Django makes:
1) 'flat' and 'named' can't be used together.
2) 'flat' is not valid when values_list is called with more than one field.
* Determine better row types for values_list/values based on fields specified.
- In the case of values_list, we use a Row type with either a single primitive, Tuple, or NamedTuple.
- In the case of values, we use a TypedDict.
- In both cases, Any is used as a fallback for individual fields if those fields cannot be resolved.
A couple other fixes I made along the way:
- Don't create reverse relation for ForeignKeys with related_name='+'
- Don't skip creating other related managers in AddRelatedManagers if a dynamic value is encountered
for related_name parameter, or if the type cannot be determined.
* Fix for TypedDict so that they are considered anonymous.
* Clean up some comments.
* Implement making TypedDict anonymous in a way that doesn't crash sometimes.
* Fix flake8 errors.
* Remove even uglier hack about making TypedDict anonymous.
* Address review comments. Write a few better comments inside tests.
* Fix crash when running with mypyc ("interpreted classes cannot inherit from compiled") due to the way I extended TypedDictType.
- Implemented the hack in another way that works on mypyc.
- Added a couple extra tests of accessing 'id' / 'pk' via values_list.
* Fix flake8 errors.
* Support annotation expressions (use type Any) for TypedDicts row types returned by values_list.
- Bonus points: handle values_list gracefully (use type Any) where Tuples are returned
where some of the fields arguments are not string literals.
* Make CharField(blank=True) not be considered nullable
The documentation on [blank](https://docs.djangoproject.com/en/2.1/ref/models/fields/#blank) says that it "will allow the entry of an empty value", which for a string is just a 0-length string. This patch allows `CharField(blank=True,...)` to no longer be considered `Optional`.
closes#38
* fixed tests for `CharField(blank=True)`
* allow blank CharField to be nullable in the constructor, but the underlying type
is str (unless `null=True`)
