Run isort as part of local and ci tests to check import order

.isort.cfg

@@ -0,0 +1,7 @@
+[settings]
+multi_line_output=5
+balanced_wrapping=true
+include_trailing_comma=true
+use_parentheses=true
+line_length=78
+lines_after_imports=2

.travis.yml

@@ -10,13 +10,15 @@ python:
 install:
   - "pip install -e ."
   - "pip install coveralls"
+  - "pip install isort"
   - "pip install pyflakes"
   - "pip install pycodestyle"
   - "pip install pylint"
   - "pip install mypy"
 
 script:
   - "coverage run --source=mnemonicode setup.py test"
+  - "isort --check-only --diff --recursive mnemonicode setup.py"
   - "pycodestyle mnemonicode setup.py"
   - "pyflakes mnemonicode setup.py"
   - "pylint -E mnemonicode setup.py"

tox.ini

@@ -1,10 +1,18 @@
 [tox]
-envlist = py34,py35,py36,py37,py38,pycodestyle,pyflakes,pylint,mypy
+envlist = py34,py35,py36,py37,py38,isort,pycodestyle,pyflakes,pylint,mypy
 
 [testenv]
 commands =
     python setup.py test
 
+[testenv:isort]
+basepython = python3
+deps =
+    isort
+skip_install = True
+commands =
+	isort --check-only --diff --recursive mnemonicode setup.py
+
 [testenv:pycodestyle]
 basepython = python3
 deps =