New tertiary build: accumulated error in finding outer-edge pair

Problem

1. Line-equation algo introduces error.
2. This error accumulates along the iteration, if we start search from each (prev+1) location
3. Error is due to the "min-dist" scheme, which ignores the actual numerical tangential error.
   

Solution

1. There has to be limitation in tangential error.
2. What would be the threshold?

Major analysis

1. Outer/inner edges are noise signal.
2. We expect that they should be 1v1 relationship, while in reality they are not due to stings and other noises.
3. Tangential Redundancy: should be defined as "if two inner points find a common outer pair, then one of them is redundant."
4. In Case #3, preserve only the 1st inner point along the tangential direction.
5. Since inner signal has bigger tangential density, we need to remove inner-edge redundancy first.
6. Bottom has the most redundancy because it is the most 2D-ish among the tertiary edges.
7. Too strict line-equation would miss out bottom band completely.
8. Too loose line-equation would carry neighbor and select wrong band.
9. Bottom has to be found through 2D measure.
   
10. We need to try the sidewall-tip idea in 1D, and ensure no redundancy in the other 1D.
11. Bottom tangential redundancy can be removed by assuming bottom depends on both edges.
    
12. W2Z Reference should use "majority" instead of "mean".

Implementation

1. Do regular tertiary search based on inner edge.
2. Do redundancy check against outer-edge along the way instead of a pre-step.
3. After inner/outer pair determined, find bottom band with inner/outer line-equation.
4. For bottom, when using minimum point-to-line distance measure, should discard redundant result (pick the first non-overlap point from sorted distance list).