calibrate edge windows

Problem

1. Later fitting needs to apply to window instead of entire main thread
2. final stitching requires no overlap in the fitted data
3. can we leave the window as it is, fit each window, and merge them afterwards?
   
4. NO, it's different from fit the entire main thread; the data used to fit Win(i+1), thought having an ov-FOV, is not necessarily the same as those used for Win(i).
5. The last sample to be interpolated in Win(i), has to use the following WIN_HALF samples, so the last sample is not the last sample in the tail-FOV of the win; same for the 1st sample of Win(i+1).
6. WIN_HALF could change depending on our tests.

Solution

1. All windows have to be calibrated, based on previous window's calibration.
2. we don't throw away window data, we just define interpolation boundaries, based on fitting window size.