Datastore cleanup (#1892)

* Start Store cleanup

* wip store cleanup

* fix iterables initiating datastores

* handle the possibility of a datastore with no holds and no its own 'create' method

* more cleanup (instances that need more than just client/data)

* missed RoleStore extras

* not sure how eslint didn't catch that tab...

* avoid re-getting the channel we already have...

* cleanup resolvers and refactor them into DataStores

* ^

* and remove

* fix some bugs

* fix lint

* fix documentation maybe?

* formatting

* fix presences

* really fix presences this time

* bad fix was bad... let;s see how bad this one is..

* forgot to save a file

* make presence resolving take userresolveables too

* fix tabs in jsdocs

* fix bad fix from last night that caused issues, with better fix...

* oops

src/structures/Presence.js

@@ -26,6 +26,8 @@ class Presence {
      * @type {?Activity}
      */
     this.activity = activity ? new Activity(this, activity) : null;
+
+    return this;
   }
 
   _clone() {