TabBar title and icon for SplitScreen

A patch to set the TabBar title and icon when using a SplitScreen.
Can't do this in the master with on_load (like the normal way) as the SplitScreen is
created later.

```ruby
split=create_split_screen(
        MyMasterScreen.new(nav_bar: true, item_type: "My"),
        MyDetailScreen.new(nav_bar: true),
        icon: "MyIcon", title: "MyTitle"
      )
```