do only select a new item from the next and pref buttons when the next selected item is not the same as the previous
this is the case for the beginning (pressing prev) and end (pressing next) of the list
synthesised not synthesised property player to omit ivar access
implemented timer based observation of player's currentTime property
KVO is not possible on this property
defined delegate protocol for informing the delegate about certain events in the recording
inform delegate about events defined in delegate protocol if it implements the necessary method
declare and set the controller as the currently playing item's delegate
pulled out detail label text creation for better reusability
implemented behaviour on recoding events (currentTime and stopPlaying)