New tox.ini and set up test/lint rules (#17)

Author: aabmass

.flake8

@@ -0,0 +1,15 @@
+[flake8]
+ignore =
+  E501  # line too long, defer to black
+  F401  # unused import, defer to pylint
+  W503  # allow line breaks before binary ops
+  W504  # allow line breaks after binary ops
+  E203  # allow whitespace before ':' (https://github.com/psf/black#slices) 
+exclude =
+  .git
+  .tox
+  CVS
+  .venv*/
+  venv*/
+  target
+  __pycache__

.gitignore

@@ -136,3 +136,5 @@ dmypy.json
 
 # Cython debug symbols
 cython_debug/
+
+.vscode/

.isort.cfg

@@ -0,0 +1,16 @@
+[settings]
+include_trailing_comma=True
+force_grid_wrap=0
+use_parentheses=True
+line_length=79
+
+; 3 stands for Vertical Hanging Indent, e.g.
+; from third_party import (
+;     lib1,
+;     lib2,
+;     lib3,
+; )
+; docs: https://github.com/timothycrosley/isort#multi-line-output-modes
+multi_line_output=3
+skip=target
+skip_glob=**/gen/*,.venv*/*,venv*/*,**/proto/*,.tox