Tab customization & direct messages tab (#1012)

* custom tabs

* custom tabs interface

* implement custom tab functionality

* add database migration

* fix bugs, improve ThemeUtils nullability handling

* implement conversationsfragment

* setup ConversationViewHolder

* implement favs

* add button functionality

* revert 10.json

* revert item_status_notification.xml

* implement more menu, replying, fix stuff, clean up

* fix tests

* fix bug with expanding statuses

* min and max number of tabs

* settings support, fix bugs

* database migration

* fix scrolling to top after refresh

* fix                                 bugs

* fix warning in item_conversation

app/src/main/res/values/dimens.xml

@@ -30,4 +30,6 @@
     <item name="wrap_content" format="integer" type="dimen">-2</item>
 
     <dimen name="preference_icon_size">20dp</dimen>
+
+    <dimen name="selected_drag_item_elevation">12dp</dimen>
 </resources>