[V3 RPC] Swap back to initial RPC library and hook into core commands (#1780)

* Switch RPC libs for websockets support

* Implement RPC handling for core

* Black reformat

* Fix docs for build on travis

* Modify RPC to use a Cog base class

* Refactor rpc server reference as global

* Handle cogbase unload method

* Add an init call to handle mutable base attributes

* Move RPC server reference back to the bot object

* Remove unused import

* Add tests for rpc method add/removal

* Add tests for rpc method add/removal and cog base unloading

* Add one more test

* Black reformat

* Add RPC mixin...fix MRO

* Correct internal rpc method names

* Add rpc test html file for debugging/example purposes

* Add documentation

* Add get_method_info

* Update docs with an example RPC call specifying parameter formatting

* Make rpc methods UPPER

* Black reformat

* Fix doc example

* Modify this to match new method naming convention

* Add more tests

docs/framework_rpc.rst

@@ -4,36 +4,60 @@
 RPC
 ===
 
-.. currentmodule:: redbot.core.rpc
-
 V3 comes default with an internal RPC server that may be used to remotely control the bot in various ways.
 Cogs must register functions to be exposed to RPC clients.
 Each of those functions must only take JSON serializable parameters and must return JSON serializable objects.
 
-To begin, register all methods using individual calls to the :func:`Methods.add` method.
+To enable the internal RPC server you must start the bot with the ``--rpc`` flag.
 
 ********
 Examples
 ********
 
-Coming soon to a docs page near you!
+.. code-block:: Python
+
+    def setup(bot):
+        c = Cog()
+        bot.add_cog(c)
+        bot.register_rpc_handler(c.rpc_method)
+
+*******************************
+Interacting with the RPC Server
+*******************************
+
+The RPC server opens a websocket bound to port ``6133`` on ``127.0.0.1``.
+This is not configurable for security reasons as broad access to this server gives anyone complete control over your bot.
+To access the server you must find a library that implements websocket based JSONRPC in the language of your choice.
+
+There are a few built-in RPC methods to note:
+
+* ``GET_METHODS`` - Returns a list of available RPC methods.
+* ``GET_METHOD_INFO`` - Will return the docstring for an available RPC method. Useful for finding information about the method's parameters and return values.
+* ``GET_TOPIC`` - Returns a list of available RPC message topics.
+* ``GET_SUBSCRIPTIONS`` - Returns a list of RPC subscriptions.
+* ``SUBSCRIBE`` - Subscribes to an available RPC message topic.
+* ``UNSUBSCRIBE`` - Unsubscribes from an RPC message topic.
+
+All RPC methods accept a list of parameters.
+The built-in methods above expect their parameters to be in list format.
+
+All cog-based methods expect their parameter list to take one argument, a JSON object, in the following format::
+
+    params = [
+        {
+            "args": [],  # A list of positional arguments
+            "kwargs": {},  # A dictionary of keyword arguments
+        }
+    ]
+
+    # As an example, here's a call to "get_method_info"
+    rpc_call("GET_METHOD_INFO", ["get_methods",])
+
+    # And here's a call to "core__load"
+    rpc_call("CORE__LOAD", {"args": [["general", "economy", "downloader"],], "kwargs": {}})
 
 *************
 API Reference
 *************
 
-.. py:attribute:: redbot.core.rpc.methods
-
-    An instance of the :class:`Methods` class.
-    All attempts to register new RPC methods **MUST** use this object.
-    You should never create a new instance of the :class:`Methods` class!
-
-RPC
-^^^
-.. autoclass:: redbot.core.rpc.RPC
-    :members:
-
-Methods
-^^^^^^^
-.. autoclass:: redbot.core.rpc.Methods
-    :members:
+Please see the :class:`redbot.core.bot.RedBase` class for details on the RPC handler register and unregister methods.