… dict assigned with None value

…default value

Reproducible build fails if the file is encoded differently depending on the current locale settings when reading README.md.

test for type_hook with initVar added

added tests for type hinting with generic collections

- Remove unused type: ignore.
- Remove asterisk import and add `__all__` with all exported names, to
  pass with the `no_explicit_reexport` mypy flag.
- Add various mypy config for developer ergonomics (prettier errors,
  printing error codes, warning about unused config, ignores and casts
  etc). Kept `warn_return_any = False` in `dacite.types` for now since there
  would have to be a lot of ignores/casts otherwise.

Also add a test to help ensure that type_hooks continues to work with a
very general Mapping implementation.

allow `is_instance` checks for arbitrary generic types
add test for `npt.NDArray` handling

mark 2 tests with `init_var_type_support`