Change refine to look for positive AND negative standard deviation changes.

Currently the refine plugin looks for if channel changes by a set number of standard deviations e.g. +10 std.

For H1:ASC-AS_DC_NSUM_OUT_DQ (where we are measuring on a fringe), the value can increase or decrease on lockloss. By only looking for an increase in std, our refinement is 25ms behind. I think this is significant and a change may make it easier to measure the time taken for light to fall off PDs in the future.

I would like refine to look for positive or negative changes of standard deviation and refine using the first change.

Example using positive standard dev. refined time= .229

Example using negative standard dev. on same lockloss refined time= .205