WIP: working on mulitiple tau method to find the lag(delay) times
TST: modified:   nsls2/tests/test_core.py
ENH: modified:   nsls2/core.py
ENH: modified:   nsls2/core.py
TST: modified   nsls2/tests/test_core.py
BUG: modified:   nsls2/core.py
Merge pull request #157 from sameera2004/lagsteps

ENH : Finding lag(delay) times for multiple tau method