Bug fix and stylus stats (quick heads up)

Summary

1. Found a bug in groove unwrapping, and previous "jump" in bottom depth is now cleared. See Detail #1
   
2. Removed another bug in groove unwrapping caused by the intermediate data windowing. See Detail #2. 
3. A new problem arose: The width data showing some local static value, i.e., changes in consecutive points are either zero or a step of size 0.1mm. I assume it's another bug and working on it.
4. I'll work on #3 for a day or so before showing the entire image results.
   

Detail

1. In the first alignment before CC analysis, we align image on the pixel level. During unwrapping, we need to refine the alignment for the extracted edges.
   
2. Previously due to RAM limit, we can't downsample the entire groove all in one shot. Instead, we need to group a number of FOVs during unwrapping and make them a "window" as a super-FOV level; then we resample within the window before finally stitching the windows together. By working on super-FOV level instead of resampling and fitting for each FOV, it's easier to see longer signal during each step, otherwise we would have to stitching FOVs during each step just to see the results. However, previously I chose window size by a fixed number of FOVs for all inner, outer edges, and bottom. This caused data loss when having to truncate the heads and tails of the FOVs, because there usually is a size gap between the inner/outer edges and the bottom. So finally I changed the entire windowing scheme to using time (e.g., 0.04sec per window) as the window size and the depth discontinuity in bottom is cleared; and we can safely backward trace data from unwrapped groove to original FOVs.