A clock that can be used by a prevalent system for all its date/time related functions.
		/// <summary>
		/// See <see cref="PrevalenceActivator.CreateEngine(System.Type, string)"/>
		/// </summary>
		/// <param name="systemType"></param>
		/// <param name="prevalenceBase"></param>
		/// <param name="formatter"></param>
		/// <param name="handler"></param>
		internal PrevalenceEngine(System.Type systemType, string prevalenceBase, BinaryFormatter formatter, ExceptionDuringRecoveryHandler handler)
		{				
			_clock = new AlarmClock();

			CommandLogReader reader = new CommandLogReader(CheckPrevalenceBase(prevalenceBase), formatter);
			RecoverSystem(systemType, reader, handler);
			_commandLog = reader.ToWriter();
			_lock = new ReaderWriterLock();
			_decorators = GetCommandDecorators(systemType);
			_paused = false;
		}