Recent emoji page isn't updated

Steps to reproduce:

• Choose an emoji from the first page (smilies)
• Switch to the recent emoji page
• Expected behaviour: the chosen emoji has been added to the page
• Actual behaviour: the chosen emoji isn't added until the page is destroyed and recreated

The recent emoji page is destroyed and recreated if you switch to any non-adjacent page, such as animals and plants, so the behaviour is inconsistent depending on which pages you switch to.

The problem occurs because the EmojiPageView doesn't know when its model has been updated. The model can keep a reference to the view (via some listener interface) to notify the view of changes, but the reference must be removed when the view is destroyed and restored when the view is recreated. I had a quick look at this but couldn't find a clean way to implement it in the current structure.