This is done in a way which should simplify abstracting it to other
types of accounts if needed in the future
Remove comment about removing singletons - we're keeping them (and probably restoring some)
IrcManager now updates its "account" reference automatically through the
AccountManager.Twitch.userChanged-signal
Remove unused IrcManager getUser-method
IrcManager::beginConnecting is no longer called asynchronously. This
might want to be reverted in a more controlled asynchronous manner.
User Accounts are now stored as Shared Pointers instead of using
references/copies everywhere
There are missing parts to the "account-based" emotes that needs to be
completed before emote completion can be considered done. For now, when
I've been testing, I've been manually injecting the oauthClient and
oauthToken to the settings file with the `user_subscriptions` scope
