simplify tox, travis / appveyor setup (#184)

* simplify tox, travis / appveyor setup

* remove coding convention checks and doc task from appveyor, as the tox setup there is just wrong

.travis.yml

@@ -3,9 +3,9 @@ dist: xenial
 
 matrix:
     include:
-        - name: "docs,lint"
+        - name: "coding-conventions & docs"
           python: "3.6"
-          env: TOXENV=docs,lint-py36
+          env: TOXENV=docs,lint
           before_install:
           after_success:
         - python: "2.7"

appveyor.yml

@@ -2,9 +2,6 @@
 
 environment:
   matrix:
-    - PROFILE: conventions
-      PYTHON_VERSION: "3.6"
-      TOXENV: "docs,lint-py36"
     - PROFILE: py27
       PYTHON_VERSION: "2.7"
       TOXENV: "py27,py27-datetime"
@@ -18,16 +15,16 @@ environment:
       PYTHON_VERSION: "3.7"
       TOXENV: "py37,py37-datetime"
 
-
 cache:
   - '%LOCALAPPDATA%\pip\Cache'
 
 version: '{branch}.{build}'
 
-install:
-  - "python.exe -m pip install tox"
-
 build: off
 
+install:
+  - pip install tox
+
 test_script:
-  - "tox.exe"
+  - python -V
+  - tox

constraints.txt

@@ -4,3 +4,4 @@
 isort >= 4.3.2
 # Needed for Appveyor as long as PY2 is supported:
 pytest < 5
+pytest-html < 2

tox.ini

@@ -7,7 +7,7 @@ envlist =
     py37,
     py38,
     docs,
-    lint-py36,
+    lint,
     coverage,
 
 skip_missing_interpreters = False
@@ -30,10 +30,9 @@ deps =
     datetime: DateTime
     -cconstraints.txt
     pytest-cov
-    pytest-html < 2
+    pytest-html
 
 [testenv:coverage]
-basepython = python2.7
 skip_install = true
 
 deps =
@@ -60,7 +59,6 @@ commands =
     isort --apply --recursive {toxinidir}/src {toxinidir}/tests {posargs}
 
 [testenv:autopep8]
-basepython = python2.7
 skip_install = true
 deps =
     -cconstraints.txt
@@ -71,7 +69,7 @@ commands =
     autopep8 --verbose --in-place --recursive --aggressive --aggressive {toxinidir}/src {toxinidir}/tests setup.py
     docformatter --in-place --recursive {toxinidir}/src {toxinidir}/tests setup.py
 
-[lint]
+[testenv:lint]
 skip_install = true
 
 deps =
@@ -98,15 +96,7 @@ commands =
 whitelist_externals =
     mkdir
 
-[testenv:lint-py36]
-basepython = python3.6
-skip_install = true
-deps = {[lint]deps}
-commands = {[lint]commands}
-whitelist_externals = {[lint]whitelist_externals}
-
 [testenv:docs]
-basepython = python3.6
 deps =
     -cconstraints.txt
     Sphinx
@@ -119,7 +109,6 @@ commands =
 
 [testenv:release]
 skip_install = true
-basepython = python2.7
 
 deps =
     -cconstraints.txt