Overhaul repository with newest bestest practices

Add typing stub file
Add metadata tests
Add missing dev dependencies
Add merge conflict check pre-commit
Add tox env for py3.9
Update license from MIT to GPL3
Update pyproject with pypi metadata
Update makefile to reduce duplication and add missing targets
Update dependencies to latest versions
Update pre-commit config to piggy back on poetry env
Update pyproject to use poetry-core
Update toxfile to use locked dependencies
Remove unused codeowners file
Remove placeholder test

.gitignore

@@ -1,4 +1,3 @@
-# ---> Python
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]
@@ -7,9 +6,6 @@ __pycache__/
 # C extensions
 *.so
 
-# MyPy
-.mypy_cache/
-
 # Distribution / packaging
 .Python
 env/
@@ -28,6 +24,7 @@ wheels/
 *.egg-info/
 .installed.cfg
 *.egg
+requirements.txt
 
 # PyInstaller
 #  Usually these files are written by a python script from a template
@@ -47,8 +44,9 @@ htmlcov/
 .cache
 nosetests.xml
 coverage.xml
-*,cover
+*.cover
 .hypothesis/
+.pytest_cache/
 
 # Translations
 *.mo
@@ -67,6 +65,8 @@ instance/
 
 # Sphinx documentation
 docs/_build/
+docs/keyosk*.rst
+docs/modules.rst
 
 # PyBuilder
 target/
@@ -93,6 +93,17 @@ ENV/
 
 # Spyder project settings
 .spyderproject
+.spyproject
 
 # Rope project settings
 .ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+
+# Pycharm
+.idea/
+.idea/vcs.xml