code: boolean checkPositionPatternAppearance( Polygon2D_F64 square , float grayThreshold ) {
  		return( checkLine(square,grayThreshold,0) || checkLine(square,grayThreshold,1));
  	}
docs: Determines if the found polygon looks like a position pattern. A horizontal and vertical line are sampled.
  At each sample point it is marked if it is above or below the binary threshold for this square. Location
  of sample points is found by "removing" perspective distortion.
  
  @param square Position pattern square.