Fix conversation list self-resorting

When deleting all messages in a conversation, the entry in the left pane
should be inserted into the alphabetical portion of the list. To keep it
in this collection, do not nullify active_at.

To ensure the list view is keeping itself correctly sorted, make sure
that resorting behavior is triggered any time a relevant attribute is
changed.

This fixes deleted conversations jumping to the top of the list, and
conversation order scrambling when getting a group or contact sync
message from our master device.

Fixes #734

// FREEBIE

js/conversation_controller.js

@@ -12,7 +12,7 @@
     var conversations = new Whisper.ConversationCollection();
     var inboxCollection = new (Backbone.Collection.extend({
         initialize: function() {
-            this.on('change:active_at', this.sort);
+            this.on('change:timestamp change:name change:number', this.sort);
             this.on('add remove change:unreadCount', this.updateUnreadCount);
 
             this.listenTo(conversations, 'add change:active_at', this.addActive);

js/models/conversations.js

@@ -283,7 +283,7 @@
             var models = this.messageCollection.models;
             this.messageCollection.reset([]);
             _.each(models, function(message) { message.destroy(); });
-            this.save({active_at: null, lastMessage: '', timestamp: null}); // archive
+            this.save({lastMessage: null, timestamp: null}); // archive
         }.bind(this));
     },
 

js/views/conversation_list_view.js

@@ -8,14 +8,15 @@
     Whisper.ConversationListView = Whisper.ListView.extend({
         tagName: 'div',
         itemView: Whisper.ConversationListItemView,
-        onChangeActiveAt: function(conversation) {
+        sort: function(conversation) {
+            console.log('sorting conversation', conversation.id);
             var $el = this.$('.' + conversation.cid);
             if ($el && $el.length > 0) {
-                if (conversation.get('active_at')) {
-                    $el.prependTo(this.el);
-                } else {
                 var index = getInboxCollection().indexOf(conversation);
+                if (index > 0) {
                     $el.insertBefore(this.$('.conversation-list-item')[index+1]);
+                } else {
+                    this.$el.prepend($el);
                 }
             }
         }

js/views/inbox_view.js

@@ -68,8 +68,8 @@
             }).render();
 
             this.inboxListView.listenTo(inboxCollection,
-                    'add change:active_at',
+                    'add change:timestamp change:name change:number',
-                    this.inboxListView.onChangeActiveAt);
+                    this.inboxListView.sort);
 
             this.searchView = new Whisper.ConversationSearchView({
                 el    : this.$('.search-results'),