Finish plugin and routing overhaul, there's a new model in town:

* Plugins all derive from Omnibot.Plugin. There still is a base plugin,
  in case we want to have another plugin backend instead of a GenServer
* All plugins are monitored by a unique Plugin.Supervisor, which is in
  turn started by the PluginSupervisor (yes this is confusing, yes it
  needs to be renamed)
* Any other auxiliary child processes may be started through the
  Plugin.children/1 function.
* By default, plugins have a CfgState process which is an Agent that
  keeps track of the plugin's configuration and state
* Plugin API is now called through the GenServer backend for better
  synchronicity.
* Very few changes to the front-facing Plugin API, which is nice

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

lib/contrib/wordbot/wordbot.ex

@@ -5,23 +5,8 @@ defmodule Omnibot.Contrib.Wordbot do
 
   @default_config wordbot_source: "words.txt", wordbot_db: "wordbot.db", words_per_round: 300, hours_per_round: 5
 
-  #def start_link(opts) do
-    #Supervisor.start_link(__MODULE__, opts[:cfg], opts)
-  #end
-
-  #@impl true
-  #def init(cfg) do
-  #  children = [
-  #    {Task.Supervisor, name: Omnibot.Contrib.Wordbot.Watchers, strategy: :one_for_one},
-  #    Wordbot.Db.child_spec(cfg[:wordbot_db]),
-  #    {Wordbot.Bot, cfg: cfg, name: Omnibot.Contrib.Wordbot.Bot},
-  #  ]
-
-  #  Supervisor.init(children, strategy: :one_for_all)
-  #end
-
   @impl true
-  def children(cfg, _state) do
+  def children(cfg) do
     [
       {Task.Supervisor, name: Omnibot.Contrib.Wordbot.Watchers, strategy: :one_for_one},
       Wordbot.Db.child_spec(cfg[:wordbot_db]),