93_PWMR.pm : add DLookBackCnt, buffer holding previouse temperatures used for PID D-Part calculation
93_PWMR.pm : add DLookBackCnt, buffer holding previouse temperatures used for PID D-Part calculationView Changes
Source: 93_PWMR.pm : add DLookBackCnt, buffer holding previouse temperatures used for PID D-Part calculation (http://sourceforge.net/p/fhem/code/10731/)