[Core] Add multiple/external cog paths support (#853)

* WIP cog path manager

* Initial working state

* Get real reloading working

* Type error thingy

* And fix the tests

* Start UI shit

* path reordering

* Add install path getter/setter and fix config syntax

* Determine bot directory at runtime

* Add UI commands for install path

* Update downloader to use install path

* Add sane install path default

* Make evaluation of cog install path lazy

* Some typing fixes

* Add another line to codeowners

* Conditionally put install path in paths

* Always put install path first

* Dont allow people to add the installdir as an additional path, guarantee install dir isn't shown with paths command

* Make shit update loaded cogs

* Add tests

* Another one

core/events.py

@@ -38,14 +38,12 @@ def init_events(bot, cli_flags):
 
             for package in packages:
                 try:
-                    bot.load_extension(package)
+                    spec = bot.cog_mgr.find_cog(package)
+                    bot.load_extension(spec)
                 except Exception as e:
                     log.exception("Failed to load package {}".format(package),
                                   exc_info=e)
-                    failed.append(package)
-
-            if failed:
-                await bot.save_packages_status()
+                    await bot.remove_loaded_package(package)
             if packages:
                 print("Loaded packages: " + ", ".join(packages))