[V3 RPC] Add basic RPC functionality (#1017)

* Add basic RPC functionality

* Add load/unload/reload rpc commands

* Reorganize without rpc_ready event

* Remove rpc ready event

* Removed bot reference from rpc module

* Close RPC server cleanly

* refactor bot

* Refactor a bit and make RPC server initialization based on a cli flag

* Fix version resolver

* standardize version getters

* Pick a new port number

redbot/__main__.py

@@ -21,6 +21,7 @@ from redbot.core.sentry_setup import init_sentry_logging
 from redbot.core.cli import interactive_config, confirm, parse_cli_flags, ask_sentry
 from redbot.core.core_commands import Core
 from redbot.core.dev_commands import Dev
+from redbot.core import rpc
 import asyncio
 import logging.handlers
 import logging
@@ -96,7 +97,7 @@ def main():
     red = Red(cli_flags, description=description, pm_help=None)
     init_global_checks(red)
     init_events(red, cli_flags)
-    red.add_cog(Core())
+    red.add_cog(Core(red))
     red.add_cog(CogManagerUI())
     if cli_flags.dev:
         red.add_cog(Dev())
@@ -141,6 +142,7 @@ def main():
         sentry_log.critical("Fatal Exception", exc_info=e)
         loop.run_until_complete(red.logout())
     finally:
+        rpc.clean_up()
         if cleanup_tasks:
             pending = asyncio.Task.all_tasks(loop=red.loop)
             gathered = asyncio.gather(*pending, loop=red.loop)