add ImageUtils.ARGB extractor.
Int -> (Int, Int, Int, Int)
add ImageUtils#neighbor
get 8-neighbor (considering out of pixels)
totyuu
impl hemming
add Attr(on_center)
- fix ImageBuidlers#findBeginPoint (when attrmap has on_center)
- add tests
Merge branch 'hemming' into develop
add Hemming