Unique function with tolerance option for HMT image processing

This function groups multiple hit points into a single hit with a specified tolerance

Hit or miss transform is a popular technique for feature extraction and object identification in a image. But its effectiveness depends on the structural element (SE) chosen. In practical cases, this results in multiple hit of a same object.

The function unique_tol is an upgraded version of tolerance function which will cluster this multiple hit points into a single hit point.