PulsarCrossCorr_v2: added output/input function  of SFT-pair/SFT list to increase efficiency, added a flag to indicate read in or output
Revert "PulsarCrossCorr_v2: added output/input function  of SFT-pair/SFT list to increase efficiency, added a flag to indicate read in or output"

This reverts commit 6471cb24ca165a5cb772c3d2df577aeb798cd01a.
pulsar_crosscorr_v2: Added output/read-in SFT-pair list function, fixed an error due to lacking of CLEANFILES.