public class NumberRangeFileFilter
Implements a file filter that examines a number in a filename to
determine acceptance. This is useful for wanting to process ranges
of numbered files in collections where each file has some name, part
of which is alphabetic and constant, and part of which is numeric.
The test is evaluated based on the rightmost natural number found in
the filename string. (It only looks in the final filename, not in other
components of the path.) Number ranges are inclusive.