hole-based raw edge extraction

1. calc ho / CC centroids
   
2. sort hos and CCs radially
3. for each ho, find its sandwich wrap CC; one of them could be missing, 
4. fast windowing-based algo:
   1. angularly windowing a hole, based on a time param for the window size
   2. in each window, extract two side-bands and only do 8-neighbor edge search to the side-bands
   3. in low-level search, by checking existence of CC nb-pixel and the CC index, do inner/outer division