[V3 i18n] Internationalise help for commands and cogs (#1143)

* Framework for internationalised command help

* Translator for class docstring of cog

* Remove references to old context module

* Use CogManagerUI as PoC

* Replace all references to RedContext

* Rename CogI18n object to avoid confusion

* Update docs

* Update i18n docs.

* Store translators in list instead of dict

* Change commands module to package, updated refs in cogs

* Updated docs and more references in cogs

* Resolve syntax error

* Update from merge

redbot/core/help_formatter.py

@@ -28,7 +28,6 @@ from collections import namedtuple
 from typing import List
 
 import discord
-from discord.ext import commands
 from discord.ext.commands import formatter
 import inspect
 import itertools
@@ -36,6 +35,8 @@ import re
 import sys
 import traceback
 
+from . import commands
+
 
 EMPTY_STRING = u'\u200b'
 
@@ -133,7 +134,12 @@ class Help(formatter.HelpFormatter):
             'fields': []
         }
 
-        description = self.command.description if not self.is_cog() else inspect.getdoc(self.command)
+        if self.is_cog():
+            translator = getattr(self.command, '__translator__', lambda s: s)
+            description = inspect.cleandoc(translator(self.command.__doc__))
+        else:
+            description = self.command.description
+
         if not description == '' and description is not None:
             description = '*{0}*'.format(description)