getChanListData
DataEntity:
BoaDataEntity.py
DES: get data for list of channels
INP: (string) type = type of data
(int list) chan = channel list
(int) phase = -1:all data; 0:phase difference; 1:phase 1; 2:phase 2
(int) flag = data flag to be used
OUT: (float) array = data of the input list of channels