Close #3333 - Add an ALECompletePost event

Add an `ALECompletePost` event along with everything needed to make it
useful for its primary purpose: fixing code after inserting completions.

* `ALEFix` can now be called with a bang (`!`) to suppress errors.
* A new `ALELintStop` command lets you stop linting, and start it later.

rplugin/python3/deoplete/sources/ale.py

@@ -49,12 +49,13 @@ class Source(Base):
 
         if event == 'Async':
             result = self.vim.call('ale#completion#GetCompletionResult')
+
             return result or []
 
         if context.get('is_refresh'):
             self.vim.command(
-                "call ale#completion#GetCompletions('ale-callback', " + \
-                "{'callback': {completions -> deoplete#auto_complete() }})"
+                "call ale#completion#GetCompletions('ale-callback', "
+                + "{'callback': {completions -> deoplete#auto_complete() }})"
             )
 
         return []