Created new class AMTimestampAccumulatorAB. This class takes a 0D data source and internally manages updates and timestamps with AM0DAccumulatorAB and AMTimestampAB class variables. I thought this was a good first step towards scrolling data because both the accumulator and the timestamp must limit/resize their arrays in identical ways. Specifying those classes in AMTimestampAccumulatorAB allows us to use non-AMDataSource-interface functionality: setDataStoredSize(...) etc.