Major dependency update (#1974)

* [V3] Stop `tmp` dir showing up

* [V3] Remove requirements.txt and declare in install_requires

* Remove requirements.txt from tox.ini

* Update and pin all dependencies and sub-dependencies

* Update for breaking changes

* Reformat

* Update docs/requirements.txt and tox.ini requirements

* Add 3.7 to identifiers and travis/tox builds

* Attempt at fixing the travis build matrix

* Attempt #2

* Attempt 3

* aiohttp.ClientSession.close() -> detach() in sync code

* Add raven-aiohttp to requirements

* Fix stuff in setup.py

 - Added discord.py back into requirements list
 - Fix typo in alabaster extra requirement

Also in the Pipfile:
 - Removed allow_prereleases and explicitly pinned black, since this is the only dep we want a prerelease for.

* Update to Rapptz/discord.py@8ccb98d395

* Add proper 3.7 build in Travis

See travis-ci/travis-ci#9815

* Which version of 3.6 does Xenial install then?

* Maybe we should stop pipenv installing useless stuff

* Nevermind, back to specific minor version

* Remove lots of WET dependency stuff

* Fix egg fragment for dependency link

redbot/core/commands/errors.py

@@ -1,4 +1,5 @@
 """Errors module for the commands package."""
+import inspect
 from discord.ext import commands
 
 __all__ = ["ConversionFailure"]
@@ -7,7 +8,8 @@ __all__ = ["ConversionFailure"]
 class ConversionFailure(commands.BadArgument):
     """Raised when converting an argument fails."""
 
-    def __init__(self, converter, argument: str, *args):
+    def __init__(self, converter, argument: str, param: inspect.Parameter, *args):
         self.converter = converter
         self.argument = argument
+        self.param = param
         super().__init__(*args)