Zina - checkpoint 3

In the third exercise, we are going to look further at ActionBar group operation feature and how to handle device orientation changing. This chapter is again going to be somewhat shorter due to a more complex implementation of this feature. It is going to be implemented at two places, firstly, when picking people from a list of all users to add them to user’s friends, secondly when creating a new message that can be sent not only to one person, but to a group of people sharing one conversation.
Last but not least, we are going to cover communication between fragments and Parcelable interface. When new friends are added in AddFriendsFragment, they are immediately sent to FriendsFragment and displayed. To do so, we must wrap the list of users so that it can be represented as a String and then unwrapped to its original structure in FriendsFragment.