Fix typing errors (#39)

* Remove obsolete option `strict_boolean`

It was removed back in 2018:
https://github.com/python/mypy/pull/5740/files

modified:   tox.ini

* Deactivate all mypy options

This still leaves 47 errors, which should be fixed one by one.

modified:   tox.ini

* Fix signature for `output`

`client_host` is either a str or None.

modified:   ssh-audit.py

* Fix return value for `output_recommendations`

It is a bool, not None.

modified:   ssh-audit.py

* Fix type comment for `output_fingerprints`

modified:   ssh-audit.py

* Fix type comment for `output_security`

modified:   ssh-audit.py

* Fix type comment for `output_security_sub`

modified:   ssh-audit.py

* Fix type comment for `output_compatibility`

modified:   ssh-audit.py

* Fix type comment for Socket.__init__

modified:   ssh-audit.py

* Simplify check for regex result

... which also fixes four typing errors.

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing errors by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix typing error by simplifying regex result check

modified:   ssh-audit.py

* Fix type comment for OutputBuffer.flush

modified:   ssh-audit.py

* Fix type comments for `output_algorithms`

modified:   ssh-audit.py

* Fix type comment for `output_algorithm`

modified:   ssh-audit.py

* Fix type comment for KexGroup14's init method

modified:   ssh-audit.py

* Fix type comment for KexDH's send_init

modified:   ssh-audit.py

* Fix type comment for KexDH's init method

modified:   ssh-audit.py

* Add explicit return value of None

Now this is odd. Python has an implicit return value of None for
`return`, but mypy does not infer that.

modified:   ssh-audit.py

* Fix type error for unknown_algorithms

modified:   ssh-audit.py

* Add type comment for Socket.__sock_map

modified:   ssh-audit.py

* Create type comment for Kex.__host_keys

modified:   ssh-audit.py

* Create type comment for Kex.__dh_modulus_sizes

modified:   ssh-audit.py

* Add type comment for Kex.__rsa_key_sizes

modified:   ssh-audit.py

* Fix type eror by adding type comment to temp variable

modified:   ssh-audit.py

* Fix type comments for Auditconf.__setattr__

modified:   ssh-audit.py

* Fix type error by simplifying branch logic

modified:   ssh-audit.py

* Do not skip type checks any more

Without additional strict options, there are zero type errors (down from
47).

modified:   tox.ini

* Annotate variables before tuple unpacking

modified:   ssh-audit.py

* Annotate variables before unpacking

modified:   ssh-audit.py

* Fix flake8 issues

modified:   ssh-audit.py

tox.ini

@@ -25,8 +25,7 @@ commands =
 	test: pytest -v --junitxml={toxinidir}/reports/junit.{envname}.xml {posargs:test}
 	test: coverage report --show-missing
 	test: coverage html -d {toxinidir}/reports/html/coverage.{envname}
-# Temporarily disable mypy, since types have been ignored since v2.0.0.
-#	py{35,36,37,38}-{type,mypy}: {[testenv:mypy]commands}
+	py{35,36,37,38}-{type,mypy}: {[testenv:mypy]commands}
 	py{py3,35,36,37,38}-{lint,pylint},lint: {[testenv:pylint]commands}
 	py{py3,35,36,37,38}-{lint,flake8},lint: {[testenv:flake8]commands}
 	py{py3,35,36,37,38}-{lint,vulture},lint: {[testenv:vulture]commands}
@@ -89,18 +88,17 @@ commands =
 
 
 [mypy]
-ignore_missing_imports = False
-follow_imports = error
-disallow_untyped_calls = True
-disallow_untyped_defs = True
-check_untyped_defs = True
-disallow_subclassing_any = True
-warn_incomplete_stub = True
-warn_redundant_casts = True
-warn_return_any = True
-warn_unused_ignores = True
-strict_optional = True
-strict_boolean = True
+; ignore_missing_imports = False
+; follow_imports = error
+; disallow_untyped_calls = True
+; disallow_untyped_defs = True
+; check_untyped_defs = True
+; disallow_subclassing_any = True
+; warn_incomplete_stub = True
+; warn_redundant_casts = True
+; warn_return_any = True
+; warn_unused_ignores = True
+; strict_optional = True
 
 [pylint]
 reports = no