Add a linkcheck test to Tox

This currently fails.

.travis.yml

@@ -25,12 +25,7 @@ env:
 - TOXENV=pypy3-unittests
 - TOXENV=flake8
 - TOXENV=markdown-lint
-- TOXENV=mkdocs-themelint
-- TOXENV=rtd-themelint
-addons:
-  apt:
-    packages:
-      linkchecker
+- TOXENV=linkchecker
 install:
 - pip install tox
 - gem install mdl
@@ -39,6 +34,8 @@ script:
 - tox
 matrix:
   fast_finish: true
+  allow_failures:
+    - env: TOXENV=linkchecker
 before_install: pip install codecov
 after_success: codecov
 deploy:

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
     py{26,27,33,34,35}-{unittests,integration,min-req},
-    flake8, markdown-lint, {mkdocs,rtd}-themelint
+    flake8, markdown-lint, linkchecker
 
 [testenv]
 passenv = LANG
@@ -23,13 +23,10 @@ whitelist_externals = mdl
 passenv = *
 commands=mdl README.md CONTRIBUTING.md docs/
 
-[testenv:{mkdocs,rtd}-themelint]
-whitelist_externals=linkchecker
-basepython=python2.7
+[testenv:linkchecker]
+basepython = python2.7
 passenv=*
-deps=
-    -rrequirements/project.txt
+deps=LinkChecker
 commands=
-    mkdocs-themelint: {envpython} -m mkdocs build --theme=mkdocs --site-dir={envtmpdir}/site --clean
-    rtd-themelint: {envpython} -m mkdocs build --theme=readthedocs --site-dir={envtmpdir}/site --clean
-    {mkdocs,rtd}-themelint: linkchecker --check-extern {envtmpdir}/site/
+    {envpython} -m mkdocs.tests.integration --output={envtmpdir}/builds
+    linkchecker --check-extern {envtmpdir}/builds/