Treat Sphinx warnings as errors (GH-832) (GH-834)

* Treat Sphinx warnings as errors (GH-832)

(cherry picked from commit 334e9ec)

* Remove unused suspicious rules

Author: zware

.travis.yml

@@ -39,7 +39,7 @@ matrix:
         - cd Doc
         - make venv
       script:
-        - make check suspicious html PYTHON="./venv/bin/python" SPHINXBUILD="./venv/bin/python -m sphinx" SPHINXOPTS="-q"
+        - make check suspicious html PYTHON="./venv/bin/python" SPHINXBUILD="./venv/bin/python -m sphinx" SPHINXOPTS="-q -W"
     - os: linux
       language: c
       compiler: clang

Doc/tools/susp-ignored.csv

@@ -324,6 +324,4 @@ whatsnew/3.5,,::,>>> addr6 = ipaddress.IPv6Address('::1')
 whatsnew/3.5,,:root,ERROR:root:exception
 whatsnew/3.5,,:exception,ERROR:root:exception
 whatsnew/changelog,,:version,import sys; I = version[:version.index(' ')]
-whatsnew/changelog,,:gz,": TarFile opened with external fileobj and ""w:gz"" mode didn't"
-whatsnew/changelog,,::,": Use ""127.0.0.1"" or ""::1"" instead of ""localhost"" as much as"
 whatsnew/changelog,,`,"for readability (was ""`"")."