Add "Show tracked topics" to User Preferences

Does what it says on the tin. Minor clean-up.

app/assets/javascripts/discourse/models/user.js.es6

@@ -146,6 +146,11 @@ const User = RestModel.extend({
     return defaultHomepage() === "latest" ? Discourse.getURL('/?state=watching') : Discourse.getURL('/latest?state=watching');
   },
 
+  @computed()
+  trackingTopicsPath() {
+    return defaultHomepage() === "latest" ? Discourse.getURL('/?state=tracking') : Discourse.getURL('/latest?state=tracking');
+  },
+
   @computed("username")
   username_lower(username) {
     return username.toLowerCase();

app/assets/javascripts/discourse/templates/preferences.hbs

@@ -263,12 +263,14 @@
       <div class="controls category-controls">
       <a href="{{unbound model.watchingTopicsPath}}">{{i18n 'user.watched_topics_link'}}</a>
       </div>
-      <div class="instructions"></div>
       <div class="controls category-controls">
         <label><span class="icon fa fa-circle tracking"></span> {{i18n 'user.tracked_categories'}}</label>
         {{category-selector categories=model.trackedCategories blacklist=selectedCategories}}
       </div>
       <div class="instructions">{{i18n 'user.tracked_categories_instructions'}}</div>
+      <div class="controls category-controls">
+      <a href="{{unbound model.trackingTopicsPath}}">{{i18n 'user.tracked_topics_link'}}</a>
+      </div>
       <div class="controls category-controls">
         <label><span class="icon fa fa-dot-circle-o watching-first-post"></span> {{i18n 'user.watched_first_post_categories'}}</label>
         {{category-selector categories=model.watchedFirstPostCategories}}

config/locales/client.en.yml

@@ -627,6 +627,7 @@ en:
       muted_users_instructions: "Suppress all notifications from these users."
       muted_topics_link: "Show muted topics"
       watched_topics_link: "Show watched topics"
+      tracked_topics_link: "Show tracked topics"
       automatically_unpin_topics: "Automatically unpin topics when I reach the bottom."
       apps: "Apps"
       revoke_access: "Revoke Access"