Tree Model 2 Electric Boogaloo

This draws heavily on what @carlschwan did in network/neochat!1579 but I found it easier to start again and grab the bits as I needed them plus some other copying from what I did in the Space tree model.

From my current limited testing this seems to work nicely try and break it.

src/enums/neochatroomtype.h

@@ -29,6 +29,7 @@ public:
         Deprioritized, /**< The room is set as low priority. */
         Space, /**< The room is a space. */
         AddDirect, /**< So we can show the add friend delegate. */
+        TypesCount, /**< Number of different types (this should always be last). */
     };
     Q_ENUM(Types);