Move corner detection from AgastDetector5_8_computeCornerScore to AgastDetector5_8_is_a_corner in preparation for next commits
Move corner detection from AgastDetector5_8_computeCornerScore to AgastDetector5_8_is_a_corner in preparation for next commits

drmateo/pcl,drmateo/pcl,drmateo/pcl,drmateo/pcl,drmateo/pcl