Added support for datatypes 7.002 (DPT_TIMEPERIOD), 7.003
(DPT_TIMEPERIOD_10), 7.004 (DPT_TIMEPERIOD_100), 7.005
(DPT_TIMEPERIOD_SEC), 7.006 (DPT_TIMEPERIOD_MIN) and 7.011 (DPT_LENGTH)
and respective testcases.