stricter checking of types

This patchset addresses #39.

we've now added the entire (default) config of flake8-mypy.
The following options deviate from their default (which gets us a step
closer to mypy --strct)

- ignore_missing_imports=False
- follow_imports=True
- cache_dir=.mypy_cache
- disallow_untyped_calls=True
- warn_return_any=True

We've also toggled these two:

- warn_redundant_casts=True
- warn_unused_ignores=True

Finally, we check for

- check_untyped_defs=True

For the full --strict set, we'd also need:

- disallow_untyped_defs=True

But that, we'll need better typedefs.

Author: igalic

setup.cfg

@@ -4,11 +4,42 @@ description-file = README.md
 [mypy]
 python_version = 3.6
 # override flake8-mypy defaults, since we provide (missing) types
+platform='freebsd'
+
+# flake8-mypy expects the two following for sensible formatting
+show_column_numbers=True
+show_error_context=False
+
 ignore_missing_imports=False
-disallow_untyped_calls=True
 follow_imports=True
 cache_dir=.mypy_cache
 
+# disallow untyped calls since we provide our own typedefs
+disallow_untyped_calls=True
+
+# don't allow just Any thing.
+warn_return_any=True
+
+# treat Optional per PEP 484
+strict_optional=True
+
+# ensure all execution paths are returning
+warn_no_return=True
+
+# lint-style cleanliness for typing needs to be disabled; returns more errors
+# than the full run.
+warn_redundant_casts=True
+warn_unused_ignores=True
+
+# The following are off by default.  Flip them on if you feel
+# adventurous.
+
+# this is okay
+check_untyped_defs=True
+# this will need better typedefs
+disallow_untyped_defs=False
+
+
 [tool:pytest]
 addopts = -v -x -rs --ignore=setup.py --pep8 --cov-report term-missing --cov=iocage/lib iocage/lib iocage/tests
 pep8maxlinelength = 80