Improve PyPI packaging (#71)

* Move files for better setup.py packaging

* Update setup.py and configs for src layout

* Run tests on setup.py build

In effect, this tests that the setup.py configuration is correct.

coverage combine and coverage:paths are added to keep the displayed
coverage paths as src/ssh_audit/*.py instead of
.tox/$envname/**/site-packages/ssh_audit/*.py

* Remove unnecessary encoding declarations

Python 3 defaults to UTF-8 encoding.
https://docs.python.org/3/reference/lexical_analysis.html#encoding-declarations

* Remove shebang from colorama type stubs

Shouldn't need to be an executable.
Related: git has this file tracked as chmod -x.

test/conftest.py

@@ -1,4 +1,3 @@
-import os
 import io
 import sys
 import socket
@@ -7,9 +6,8 @@ import pytest
 
 @pytest.fixture(scope='module')
 def ssh_audit():
-    __rdir = os.path.join(os.path.dirname(os.path.abspath(__file__)), '..')
-    sys.path.append(os.path.abspath(__rdir))
-    return __import__('ssh-audit')
+    import ssh_audit.ssh_audit
+    return ssh_audit.ssh_audit
 
 
 # pylint: disable=attribute-defined-outside-init

test/stubs/colorama.pyi

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
 from typing import Optional
 
 def init(autoreset: bool = False, convert: Optional[bool] = None, strip: Optional[bool] = None, wrap: bool = True) -> None: ...