Run pylint on addons providing a buld breaker on travis (#2011)

* Run pylint (using a pylintrc file) on the addon Python scripts. It serves as a build breaker for severe issues.
* Skip y2038 addon for now until it's fixed.

.travis.yml

@@ -20,6 +20,7 @@ before_install:
  - travis_retry sudo apt-get update -qq
  - travis_retry sudo apt-get install -qq python-pygments qt5-default qt5-qmake qtbase5-dev qtcreator libxml2-utils libpcre3 gdb unzip wx-common xmlstarlet
  - travis_retry sudo python2 -m pip install --upgrade pytest==4.6.4
+ - travis_retry python2 -m pip install --user pylint
 
 matrix:
 # do notify immediately about it when a job of a build fails.
@@ -84,6 +85,11 @@ matrix:
 # check python syntax by compiling all addon scripts
         - python -m compileall ./addons
         - python3 -m compileall ./addons
+# run pylint
+        - cd addons
+#        - pylint *.py y2038/*.py ! First resolve https://trac.cppcheck.net/ticket/9210 "y2038 addon no longer working"
+        - pylint *.py
+        - cd ..
 # check python syntax by compiling some selected scripts
         - python -m py_compile ./tools/donate-cpu.py
         - python3 -m py_compile ./tools/donate-cpu.py

addons/pylintrc

@@ -0,0 +1,5 @@
+# Just the severe stuff...
+[MESSAGES CONTROL]
+disable=C,R,W
+[REPORTS]
+reports=no