Add pycodestyle Python linter support (#872)

Add a pycodestyle linter

doc/ale-python.txt

@@ -122,6 +122,35 @@ g:ale_python_mypy_use_global                     *g:ale_python_mypy_use_global*
   See |ale-integrations-local-executables|
 
 
+===============================================================================
+pycodestyle                                            *ale-python-pycodestyle*
+
+
+g:ale_python_pycodestyle_executable       *g:ale_python_pycodestyle_executable*
+                                          *b:ale_python_pycodestyle_executable*
+  Type: |String|
+  Default: `'pycodestyle'`
+
+  See |ale-integrations-local-executables|
+
+
+g:ale_python_pycodestyle_options             *g:ale_python_pycodestyle_options*
+                                             *b:ale_python_pycodestyle_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be changed to add command-line arguments to the
+  pycodestyle invocation.
+
+
+g:ale_python_pycodestyle_use_global       *g:ale_python_pycodestyle_use_global*
+                                          *b:ale_python_pycodestyle_use_global*
+  Type: |Number|
+  Default: `0`
+
+  See |ale-integrations-local-executables|
+
+
 ===============================================================================
 pylint                                                      *ale-python-pylint*
 

doc/ale.txt

@@ -96,6 +96,7 @@ CONTENTS                                                         *ale-contents*
       flake8..............................|ale-python-flake8|
       isort...............................|ale-python-isort|
       mypy................................|ale-python-mypy|
+      pycodestyle.........................|ale-python-pycodestyle|
       pylint..............................|ale-python-pylint|
       yapf................................|ale-python-yapf|
     ruby..................................|ale-ruby-options|