If we have removed a stream from the home view, and our pointer
that we load from the server refers to a message that is no longer
visible, we don't want to error out but rather select the nearest
message to our previously selected one.
(imported from commit d212f1fba7b06836d1d916b43042991625b6f41e)
Messages are now selected on a MessageList, which triggers a
message_selected event that other parts of the code can listen for.
(imported from commit 1da9e4121425c0ac4461b41b7aea169072e1512b)